I need help figuring out the reason behind my algae problem.

[Finatic005]

Hello Fishlore,

I have a 20 gallon long aquarium, with a lot of guppies and endlers (like 40 or 50 of them), an albino Cory (the others died a while back, this one is still going by itself, and I really don’t want more; she just laid eggs, too), 8 24kt gold mountain minnows, a nerite snail, some pest snails, and 3 amano shrimp. I have a big algae problem and I can’t figure out why it is growing so rapidly and so much of it. This tank is planted, and it has an established denitrifying process that keeps the nitrates @ 0ppm. As far as the plants, there is a lot of Italian Val, two large anubias, and two other plants that attach to the rocks. The Val is the only plant that seems to be growing, the rest are staying the same. I fertilize once a week (three pumps of thrive s, one pump for every 5 gallons and about 5 of the 20 gallons are taken up by substrate) and the lights are on for 10 hours a day. I feed the fish once a day with tetra flakes and also two omega one shrimp pellets for the cat fish and the shrimp, but the guppies like to eat it too. I’m wondering if maybe I’m overfeeding, but I have no way of knowing myself. I’m wondering if anyone out there knows? I’d really be more into the tank if it didn’t look so ugly with all of the algae. I have some gorgeous guppies and endlers in there, some of which are hybrids (guppy-endler cross). One more thing I had to mention: the snails are randomly dying. I don’t know why but I used to have four mystery snails and two nerite snails. all of the mystery snails died and only one of the nerites is still alive. I use fish food that is copper free, fertilizer that is copper free, and everything else is copper free as well. Snails have always died in this tank. I even used to have a bunch of ramshorn’s that suddenly died as well. Anyway, my main problem is the allergy so I’m wondering if anyone can help me with that. I just removed a bunch of algae right before I wrote this, so the algae isn’t bad right now.

the ph= 7.8
Temp= 72-75
Ferts= Thrive S
Lights= two medium bright LED’s meant for planted tanks 10hrs/day
Filters= two sponge filters (one meant for 20 gallons, the other is meant for 50 gallons) and one eheim classic filter. I don’t remember what it is rated for.
Thanks for any help!!

 

[AllAboutAngelfish]

try a plant called pearlweed it will suck up exess nutrients causing algea to die out (it may not work imediently)

 

[Finatic005]

try a plant called pearlweed it will suck up exess nutrients causing algea to die out (it may not work imediently)

Ok, I will consider that, but couldn’t the problem be a lack of nutrients? Like the algae is taking over because there aren’t enough nutrients for the plants to grow there’s enough for the algae to grow?

 

[StarGirl]

How long are your lights on and What fert do you use?

 

[Finatic005]

How long are your lights on and What fert do you use?

My lights are on for 10hrs a day on a timer and the fert I use is thrive S once a week, three pumps (when one pump per 15 gallons, minus the five gallons of substrate=15 gallons of water in the tank)

 

[AllAboutAngelfish]

Ok, I will consider that, but couldn’t the problem be a lack of nutrients? Like the algae is taking over because there aren’t enough nutrients for the plants to grow there’s enough for the algae to grow?

What im saying is that the source is the exess nutrients and if the source is terminiated the algae whould die out eventually

Alage feeds on those exess nutrients, and if thers no no nutrients left for algae It will die and other plants should be fine


Check out MD fishtanks on youtube hhe explains it in some of his videos + he never has to worry about algea because of pearlweed

 

[StarGirl]

My lights are on for 10hrs a day on a timer and the fert I use is thrive S once a week, three pumps (when one pump per 15 gallons, minus the five gallons of substrate=15 gallons of water in the tank)

Bump your light down to about 7 hrs. See if that helps. Usually too much light is the main culprit. I dose my Thrive C 1 pump per 5 gallons. What is the Thrive S dose supposed to be? I just do the whole volume of my tank. So 55g I do 11 pumps, 5g 1 pump. I dont figure in decor. You have a bunch of plants I would try dosing twice a week. Your plants need to out compete the algae.

 

[PascalKrypt]

Ok, I will consider that, but couldn’t the problem be a lack of nutrients? Like the algae is taking over because there aren’t enough nutrients for the plants to grow there’s enough for the algae to grow?

Algae grow when there are nutrients that aren't being taken up by anything else. This could be because your plants are not able to sufficiently use the available nutrients to grow (as in, something else is preventing them from thriving, leaving space for algae to thrive instead) or there is simply so much available in the way of nutrients (and light) that your plants can't keep up and algae fill that gap.

Based on your photos my guess would be the latter. Your tank is quite strongly stocked with fish that produce a bunch of waste and I see a *ton* of pest snails, which suggests that quite a lot of food is going to waste in the substrate or where ever. Out of the plants you have, only the vallisneria could be classified as a medium to fast grower that might soak up some nutrients.
Here is a bunch of things that you might try (some I see have already been suggested), multiple at once may be needed to fix the problem.
- reduce amount fed in feedings - also watch and check to see if all the flakes are being eaten or if stuff disappears at the bottom.
- clean the substrate with a good vacuum to make sure nothing is decaying down there
- reduce the # of hours the lights are on daily. You can also introduce a lighting break (4 hours of light, 2 hours off, 4 hours of light) which encourages plant growth over algae growth
- check if your lights aren't simply too bright. None of the plants in your tank need a lot of light, overly bright lighting also tends to encourage algae.
- stop dosing fertiliser or reduce scheduled dosings for a few weeks and see what happens. If algae is thriving more than your plants, then that is likely where your efforts with ferts are going which would be a waste
- reduce stocking if you happen to have other tanks available

 

[Finatic005]

What im saying is that the source is the exess nutrients and if the source is terminiated the algae whould die out eventually

Alage feeds on those exess nutrients, and if thers no no nutrients left for algae It will die and other plants should be fine


Check out MD fishtanks on youtube hhe explains it in some of his videos + he never has to worry about algea because of pearlweed

Great, thanks!

Bump your light down to about 7 hrs. See if that helps. Usually too much light is the main culprit. I dose my Thrive C 1 pump per 5 gallons. What is the Thrive S dose supposed to be? I just do the whole volume of my tank. So 55g I do 11 pumps, 5g 1 pump. I dont figure in decor. You have a bunch of plants I would try dosing twice a week. Your plants need to out compete the algae.

I'll try that. I did used to have it on for 12hrs, but I moved it down to 10hrs about six months ago and it helped a lot. The algae came back later. The thrive S has the same dose. I do three pumps because I have about 5 gallons of substrate in the 20 gallon tank already. I do three pumps a week. You suggest dosing twice a week; could the plants really not be receiving enough nutrients? I have a decently large amount of fish so I assumed that it would be enough. How should I go about dosing twice a week? (since there are 7 days in a week, the dosings will not be evenly distributed throughout the week.) Thanks for all the help!!

 

[Finatic005]

Algae grow when there are nutrients that aren't being taken up by anything else. This could be because your plants are not able to sufficiently use the available nutrients to grow (as in, something else is preventing them from thriving, leaving space for algae to thrive instead) or there is simply so much available in the way of nutrients (and light) that your plants can't keep up and algae fill that gap.

Based on your photos my guess would be the latter. Your tank is quite strongly stocked with fish that produce a bunch of waste and I see a *ton* of pest snails, which suggests that quite a lot of food is going to waste in the substrate or where ever. Out of the plants you have, only the vallisneria could be classified as a medium to fast grower that might soak up some nutrients.
Here is a bunch of things that you might try (some I see have already been suggested), multiple at once may be needed to fix the problem.
- reduce amount fed in feedings - also watch and check to see if all the flakes are being eaten or if stuff disappears at the bottom.
- clean the substrate with a good vacuum to make sure nothing is decaying down there
- reduce the # of hours the lights are on daily. You can also introduce a lighting break (4 hours of light, 2 hours off, 4 hours of light) which encourages plant growth over algae growth
- check if your lights aren't simply too bright. None of the plants in your tank need a lot of light, overly bright lighting also tends to encourage algae.
- stop dosing fertiliser or reduce scheduled dosings for a few weeks and see what happens. If algae is thriving more than your plants, then that is likely where your efforts with ferts are going which would be a waste
- reduce stocking if you happen to have other tanks available

Thank you so much. For your first point, I have been thinking about the same thing. I am always worried that they'll not attain enough food. Is there a way to tell if I am feeding enough?

I do use a vacuum to clean the substrate, a lot of stuff comes up.

I will consider the lighting break if my new lighting schedule (7hrs/day) isn't sufficient enough. I believe my lights are nicrew LED's, which I have heard aren't that bright compared to other lights on the market.

I am confused whether to increase dosings of ferts or decrease them, because I have seen both methods suggested. Any more information on this would be greatly appreciated.

I don't have any other tanks available, but I am going to consider selling some or giving them away to a breeder or well-maintained lfs... because I want them going somewhere that will take care of them. Again, thanks for the help.

 

[StarGirl]

I would say hold off on the ferts like Pascal said and start to work on the substrate cleaning and light reduction.

 

[Finatic005]

I would say hold off on the ferts like Pascal said and start to work on the substrate cleaning and light reduction.

OK, thank you. If I reduce the ferts, should I reduce the number of fish as well? Or instead of that, buy some easy-to-grow, fast-growing plants? Or both?

 

[StarGirl]

For now lets just try stopping the ferts. Clean the substrate better, Reduce light and see if that helps. Once that is cleaned up some you can go from there. Algae is a tricky bugger.

 

[Finatic005]

For now lets just try stopping the ferts. Clean the substrate better, Reduce light and see if that helps. Once that is cleaned up some you can go from there. Algae is a tricky bugger.

Ok, I will do so. I will give any updates if this works or needs a little extra help.

Thanks so much!

 

[PascalKrypt]

Thank you so much. For your first point, I have been thinking about the same thing. I am always worried that they'll not attain enough food. Is there a way to tell if I am feeding enough?

I do use a vacuum to clean the substrate, a lot of stuff comes up.

I will consider the lighting break if my new lighting schedule (7hrs/day) isn't sufficient enough. I believe my lights are nicrew LED's, which I have heard aren't that bright compared to other lights on the market.

I am confused whether to increase dosings of ferts or decrease them, because I have seen both methods suggested. Any more information on this would be greatly appreciated.

I don't have any other tanks available, but I am going to consider selling some or giving them away to a breeder or well-maintained lfs... because I want them going somewhere that will take care of them. Again, thanks for the help.

Ah, I stupidly forgot another option I intended to write, as AllAboutAngelfish proposed, that is to add some robust fast-growing plants to outcompete the algae. Other than pearlweed, options are anacharis, ceratophyllum, hygrophila, bacopa, rotala, and floaters like duckweed, salvinia and pistia that outcompete algae by having prime access to oxygen - though floaters also risk blocking out light from your other plants, so keep an eye on that if you decide to try them.

As for the food question, just keep an eye on your fish from day to day. You'll be able to tell if your guppies are losing weight. If you feed less for a week or two and nothing appears to change, feeding them that much is fine and everything on top of that likely contributes to algae. You might want to keep an eye on your cories though, to make sure they get enough (as they tend to be outcompeted by boisterous top and mid level swimmers). Small fish that eat every day really don't need more than tiny portions each.

As for the snails dying, you might want to test your water hardness. I have trouble keeping shrimp and snails other than pests due to having a GH <4 in my tap (PH is around 7.8 though, strangely).

So the problem people likely have with encourage you to increase or decrease ferts is because of what I wrote at the top of my previous post. Algae thriving could be because your plants are failing to thrive, or it could be because of an excess of nutrients in the water column. It can be difficult to distinguish between these situations and they need opposite solutions, because cutting down on nutrients if your plants are already failing due to a lack makes the problem worse; where if the problem is an excess of nutrients, dosing more ferts will make the problem worse.
My reason for thinking you should cut down on them and the lighting is because the large number of pond snails and the looks of the plants (which seem to be growing fine) both point at there being an excess.

 

[GlennO]

What does your nitrate level generally run at? That can sometimes be a guide as to whether excess or lack of nutrients could be contributing to algae (as well as lighting). I suspect that you would have rather high levels (and possibly phosphates too) given the number of fish, so the previous advice regarding waste management, stopping ferts temporarily and introducing more fast growing plants is probably on the mark. Plants do need other nutrients though and there are plenty of nitrate & phosphate free fertilisers. Thrive contains both.

 

[Finatic005]

Ah, I stupidly forgot another option I intended to write, as AllAboutAngelfish proposed, that is to add some robust fast-growing plants to outcompete the algae. Other than pearlweed, options are anacharis, ceratophyllum, hygrophila, bacopa, rotala, and floaters like duckweed, salvinia and pistia that outcompete algae by having prime access to oxygen - though floaters also risk blocking out light from your other plants, so keep an eye on that if you decide to try them.

As for the food question, just keep an eye on your fish from day to day. You'll be able to tell if your guppies are losing weight. If you feed less for a week or two and nothing appears to change, feeding them that much is fine and everything on top of that likely contributes to algae. You might want to keep an eye on your cories though, to make sure they get enough (as they tend to be outcompeted by boisterous top and mid level swimmers). Small fish that eat every day really don't need more than tiny portions each.

As for the snails dying, you might want to test your water hardness. I have trouble keeping shrimp and snails other than pests due to having a GH <4 in my tap (PH is around 7.8 though, strangely).

So the problem people likely have with encourage you to increase or decrease ferts is because of what I wrote at the top of my previous post. Algae thriving could be because your plants are failing to thrive, or it could be because of an excess of nutrients in the water column. It can be difficult to distinguish between these situations and they need opposite solutions, because cutting down on nutrients if your plants are already failing due to a lack makes the problem worse; where if the problem is an excess of nutrients, dosing more ferts will make the problem worse.
My reason for thinking you should cut down on them and the lighting is because the large number of pond snails and the looks of the plants (which seem to be growing fine) both point at there being an excess.

I will probably look into quickly-growing plants if these many other options fail. When I very first set up the tank, I had duckweed and hornwort. They all died within the first few months. In fact, almost every single plant I have ever gotten has died... it is very confusing. The plants that are currently in the tank are the only species that have survived. I got all of those plants (except the val) back in April or May and they have not grown AT ALL. They are the same size as when they arrived on my door step. I do not have very much success with plants unfortunately, and maybe I should start another thread for my plant issues- haha.

I can tell, as of now, that the cory is fat and happy. She (I know it is a she due to the eggs she just laid) gets more than enough food (which implies I am feeding too much). I will test the gH. The last time I tested it, it was an 8 (out of the tap). Obviously I knew that was really high, but after all of my research on snails, I failed to realize that a high gH can harm them- thank you for informing me. The pH of the water out of my tap is 8.2, but it drops back to 7.8 once it has been in the tank for a while.

Your reasoning on the cutting versus raising the nutrients makes perfect sense. I will absolutely cut back on them- stopping dosing entirely, whilst feeding less. Hopefully this will balance out. How will I know if I shift from too many nutrients to not enough? Like say I stop dosing and feed less, but algae continues. How would I know if it was still too much or too little?

Thanks!

 

[Finatic005]

What does your nitrate level generally run at? That can sometimes be a guide as to whether excess or lack of nutrients could be contributing to algae (as well as lighting). I suspect that you would have rather high levels (and possibly phosphates too) given the number of fish, so the previous advice regarding waste management, stopping ferts temporarily and introducing more fast growing plants is probably on the mark. Plants do need other nutrients though and there are plenty of nitrate & phosphate free fertilisers. Thrive contains both.

My nitrates are always at 0 due to my denitrification process. If I were to guess, my phosphates are probably high, although I'd have to test them to find out. So I don't believe the nitrates are the culprit of the algae. If you have anymore info, I'd love to hear! Thanks

 

[GlennO]

My nitrates are always at 0 due to my denitrification process. If I were to guess, my phosphates are probably high, although I'd have to test them to find out. So I don't believe the nitrates are the culprit of the algae. If you have anymore info, I'd love to hear! Thanks

Ideally the phosphate/nitrate ratio should be around 1:10. So if you're removing all nitrates and have high phosphate levels that would be an issue. In fact just having 0 nitrates in a planted tank is an issue in itself.

What denitrification process are you using and what is the motivation for that rather than water changes? Do you have nitrates in your tap water?

 

[LeviS]

I'm going to chime in here, if your running 2 nicrew classic led lights on a 20 long for 10 hours, that's 1 reason for the algae as thats over 100 par in your tank at 12". Definitely would be needing to run co2.
I recommend identifying your lights, research them and the par rating at 12" since you have a 20 long.
If there are no nitrates in the water due to plants or denitrification process that's another issue as plants need nitrates to thrive. Algae needs far less and can thrive off other nutrients besides nitrates.
As others have stated cut back your lights, I recommend 6 hours but 7 may work. I would research the plants you have in the tank and dose ferts based on the directions maybe a little less. Jungle val feeds through roots but also some from water column so root tabs may be sufficient.

Edit: i re-read your post. I recommend cutting lights back to 7 hours, stop dosing liquid ferts, swap to root tabs for the val. Anubias is a very slow grower and does not take much for ferts. Clean what algae you can with a toothbrush and maintain water changes, you should be good to go.

 

[Finatic005]

Ideally the phosphate/nitrate ratio should be around 1:10. So if you're removing all nitrates and have high phosphate levels that would be an issue. In fact just having 0 nitrates in a planted tank is an issue in itself.

What denitrification process are you using and what is the motivation for that rather than water changes? Do you have nitrates in your tap water?

I have extra-deep substrate that has anoxic zones where anaerobic bacteria thrive. These bacteria consume the nitrates and convert them into nitrogen gas bubbles. I believe my tap water has nitrates in it. If I remember correctly, it is 5 or 10ppm. My fertilizer has nitrates in it- but I am being informed that I need to cut back on ferts for now. I am a student, and an athlete. I have an immensely packed schedule. I did this system so that if I couldn't get to the water change for a week or two or even longer, the tank would be ok. This has worked well with the fish, but obviously has impacted the plants and algae.

I'm going to chime in here, if your running 2 nicrew classic led lights on a 20 long for 10 hours, that's 1 reason for the algae as thats over 100 par in your tank at 12". Definitely would be needing to run co2.
I recommend identifying your lights, research them and the par rating at 12" since you have a 20 long.
If there are no nitrates in the water due to plants or denitrification process that's another issue as plants need nitrates to thrive. Algae needs far less and can thrive off other nutrients besides nitrates.
As others have stated cut back your lights, I recommend 6 hours but 7 may work. I would research the plants you have in the tank and dose ferts based on the directions maybe a little less. Jungle val feeds through roots but also some from water column so root tabs may be sufficient.

Edit: i re-read your post. I recommend cutting lights back to 7 hours, stop dosing liquid ferts, swap to root tabs for the val. Anubias is a very slow grower and does not take much for ferts. Clean what algae you can with a toothbrush and maintain water changes, you should be good to go.

I have considered CO2, because it would help remove the algae and benefit the plants/environment greatly. The only problem is: Since my tap water has a pH of 8.2, and CO2 brings the pH down, how shall I do water changes without shocking everything that is alive in the tank? I would love to attach a CO2 system if I could figure all of that out.

I see no way of adding nitrates besides a fertilizer. I could potentially get an all-nitrogen fertilizer, which would remove all of the phosphate and trace minerals. That's the only thing I can think of, although the nitrates from that fert would be quickly eliminated by the denitrification process.

I already use root tabs for the val. I also forgot to mention that there are two purple/brown crypts in the tank that are growing very slowly, but noticeably. I also use Thrive S root tabs for the crypts, once every four months (which is the dosing on the directions). It's good to know that anubias doesn't need many nutrients. I will use the toothbrush- I haven't done that yet and I honestly have no idea why. Thanks for all of the super helpful information!!!

 

[PascalKrypt]

I have extra-deep substrate that has anoxic zones where anaerobic bacteria thrive. These bacteria consume the nitrates and convert them into nitrogen gas bubbles. I believe my tap water has nitrates in it. If I remember correctly, it is 5 or 10ppm. My fertilizer has nitrates in it- but I am being informed that I need to cut back on ferts for now. I am a student, and an athlete. I have an immensely packed schedule. I did this system so that if I couldn't get to the water change for a week or two or even longer, the tank would be ok. This has worked well with the fish, but obviously has impacted the plants and algae.

I have considered CO2, because it would help remove the algae and benefit the plants/environment greatly. The only problem is: Since my tap water has a pH of 8.2, and CO2 brings the pH down, how shall I do water changes without shocking everything that is alive in the tank? I would love to attach a CO2 system if I could figure all of that out.

I see no way of adding nitrates besides a fertilizer. I could potentially get an all-nitrogen fertilizer, which would remove all of the phosphate and trace minerals. That's the only thing I can think of, although the nitrates from that fert would be quickly eliminated by the denitrification process.

I already use root tabs for the val. I also forgot to mention that there are two purple/brown crypts in the tank that are growing very slowly, but noticeably. I also use Thrive S root tabs for the crypts, once every four months (which is the dosing on the directions). It's good to know that anubias doesn't need many nutrients. I will use the toothbrush- I haven't done that yet and I honestly have no idea why. Thanks for all of the super helpful information!!!

So this changes the picture a bit. You may have denitrifying bacteria but there are other reasons for doing water changes than simply getting rid of nitrates. Plants in particular, but also the fish and in general the chemistry balance of the tank's microculture depend on all sorts of trace minerals that we do not test for. Plants also depend on larger quantities of kalium and phosphate that aren't produced by bacteria in your tank. Water changes replenish all of these as they are continually being used up. Algae as simpler live forms tend to thrive in place of plants when the chemical balance in a tank is lopsided because they can deal more efficiently with the situation than the more complex plants which require some of all the different nutrients to grow well.
In this case, aside from the other things that have been proposed, you might try more frequent water changes -- or if you don't have the time, larger ones (like 50%) when you do do them.

 

[Finatic005]

So this changes the picture a bit. You may have denitrifying bacteria but there are other reasons for doing water changes than simply getting rid of nitrates. Plants in particular, but also the fish and in general the chemistry balance of the tank's microculture depend on all sorts of trace minerals that we do not test for. Plants also depend on larger quantities of kalium and phosphate that aren't produced by bacteria in your tank. Water changes replenish all of these as they are continually being used up. Algae as simpler live forms tend to thrive in place of plants when the chemical balance in a tank is lopsided because they can deal more efficiently with the situation than the more complex plants which require some of all the different nutrients to grow well.
In this case, aside from the other things that have been proposed, you might try more frequent water changes -- or if you don't have the time, larger ones (like 50%) when you do do them.

Ok, thank you. This helps. I usually do a large 60-70% water change when I do do it. I am wanting to start doing more water changes with the same size (60-70%) to see if that helps the overall general health of the tank. Along with this, I am going to feed less and lower the amount of light. On top of all of that, I am going to discontinue the use of liquid ferts entirely. If this prevails, there shall not be a need for some fast growing plants. If I missed anything, please let me know. Thank you!

 

[GlennO]

I think the algae problem is a combination of excessive lighting and the removal of all nitrates.

Thrive C is formulated for low tech tanks. It shouldn’t be causing any algae issues if used as directed but you do need to do regular water changes. 10ppm nitrate in your tap water would not be a big issue. If you want to stop using liquid fertiliser then by all means give it a try. However I find it easier to manage algae when using fertiliser than when not because algae will take advantage of any lack of nutrients.

Your pH is not a problem re CO2 which you could look into if you wish. However it’s not a magic solution for algae. You still need to balance lighting, nutrients & CO2 levels. It's just that it’s easier to do than in a low tech tank.

 

[Finatic005]

I think the algae problem is a combination of excessive lighting and the removal of all nitrates.

Thrive C is formulated for low tech tanks. It shouldn’t be causing any algae issues if used as directed but you do need to do regular water changes. 10ppm nitrate in your tap water would not be a big issue. If you want to stop using liquid fertiliser then by all means give it a try. However I find it easier to manage algae when using fertiliser than when not because algae will take advantage of any lack of nutrients.

Your pH is not a problem re CO2 which you could look into if you wish. However it’s not a magic solution for algae. You still need to balance lighting, nutrients & CO2 levels. It's just that it’s easier to do than in a low tech tank.

I am first going to try reducing the use of the liquid ferts, starting by cutting it off entirely. If that worsens the problem, then at least I know the solution is that I don't have enough nutrients for the plants to consume. If I reach that point, I'll start using more ferts and keep the lighting at 7hrs. If that doesn't work, I'll look into CO2. Just out of curiosity- how wouldn't the pH be a problem during water changes? I'd love to know. Thanks so much!

 

[GlennO]

Just out of curiosity- how wouldn't the pH be a problem during water changes? I'd love to know. Thanks so much!

I run CO2 about 7hrs daily and I tend to do my water changes before CO2 injection starts so there’s not much change in pH as a result of the water change. I keep mostly Rainbowfish and my tap water pH is about 7.6 which drops to around 6.8 with my current rate of CO2 injection. I’ve never noticed any adverse effects.

 

[Finatic005]

I run CO2 about 7hrs daily and I tend to do my water changes before CO2 injection starts so there’s not much change in pH as a result of the water change. I keep mostly Rainbowfish and my tap water pH is about 7.6 which drops to around 6.8 with my current rate of CO2 injection. I’ve never noticed any adverse effects.

Oh ok, thank you