Should i be worried about my low pH in co2 injected tank?

courtneylm
  • #1
I have a 120g planted tank that I've finally gotten the injected co2 figured out in. However when I tested my water tonight, the pH is reading between 6 and 6.4. I know co2 lowers pH, and I also know that it's typically better to just leave pH alone and stable rather than trying to achieve a particular number. However do you think this is too low? My stocking is as follows:
4 angelfish
6 Boesemani rainbowfish
6 odessa barbs
7 upside down catfish
3 kuhli loaches
1 senegal bichir
1 siamese algae eater
1 bn pleco
Various snails

I'm okay with leaving it that low as long as it won't bother my fish. Some of my rainbowfish have stress stripes. I also noticed my nitrates are around 80. I dosed with thrive+ this morning, I'm not sure if that affects the nitrates? I just did a water change yesterday as well and dosed thrive+ all last week (3 times). I can post about nitrates in the correct forum but wanted to mention it in case it is relevant to the pH for some reason. Ammonia and nitrites are at .25 ppm or less. Prime was added yesterday.
 
Frank the Fish guy
  • #2
The key number is the C02 concentration. There is a relationship between pH, KH and C02. You can google it. Too much C02 (> 30 ppm) is toxic to fish. C02 lowers pH. But it is the C02 that harms the fish. They can't breath.

If your pH started at 7.5, and after C02 it is down at 6, then you have too much C02 and may be harming the fish. But we would have to know your normal pH before C02. Changes of more than 1 point are too much usually.

Many of us use a C02 drop checker to keep C02 levels in the 'green zone'.
 
Twocoffees
  • #3
I would be more concerned about the ammonia and nitrates then the PH. I would tackle that first before worrying about PH. I prefer Seachem Prime to Thrive+, because you can't really overdose on it. Do a big water change immediately. I would then go to your local fish store and get prime and double dose the tank. Once your ammonia readings are 0 you can then tackle your PH.

Do you know what your water's natural PH is? I would recommend reading the level right out of the tap. Then let the water sit overnight and read the PH again. If your PH is 7.0/7.5 out of the tap and then drops the next day (which is super common for people on city water lines), it means that you need to add minerals to your water to keep your PH steady. I recommend salty shrimp mineral. My water PH right out of the tap is 6.5, and I'm able to keep it at a steady 7.0 by using salty shrimp mineral. I buy it on Amazon. Unfortunately it is $$
 
GlennO
  • #4
Please confirm your tap water pH as well as your KH and how many hours per day are you injecting CO2?

Yes, Thrive+ contains nitrate so you're either adding too much or not changing enough water per week (or both).
 
courtneylm
  • Thread Starter
  • #5
Let me preface all of this by saying that I wrote this post yesterday and only posted it today. So everything I wrote is a day behind, my apologies.

The key number is the C02 concentration. There is a relationship between pH, KH and C02. You can google it. Too much C02 (> 30 ppm) is toxic to fish. C02 lowers pH. But it is the C02 that harms the fish. They can't breath.

If your pH started at 7.5, and after C02 it is down at 6, then you have too much C02 and may be harming the fish. But we would have to know your normal pH before C02. Changes of more than 1 point are too much usually.

Many of us use a C02 drop checker to keep C02 levels in the 'green zone'.
I have a drop checker, it's been green, I'm constantly checking it throughout the day to make sure it's staying the same. Before co2 my pH was only around 6.6 maybe 6.5, and that is what it comes out of the tap at.
I would be more concerned about the ammonia and nitrates then the PH. I would tackle that first before worrying about PH. I prefer Seachem Prime to Thrive+, because you can't really overdose on it. Do a big water change immediately. I would then go to your local fish store and get prime and double dose the tank. Once your ammonia readings are 0 you can then tackle your PH.

Do you know what your water's natural PH is? I would recommend reading the level right out of the tap. Then let the water sit overnight and read the PH again. If your PH is 7.0/7.5 out of the tap and then drops the next day (which is super common for people on city water lines), it means that you need to add minerals to your water to keep your PH steady. I recommend salty shrimp mineral. My water PH right out of the tap is 6.5, and I'm able to keep it at a steady 7.0 by using salty shrimp mineral. I buy it on Amazon. Unfortunately it is $$
I use prime, but it's not a fertilizer so I'm not sure why I would use that and not thrive, maybe you're thinking a different thrive? The one I'm referring to is an all in one plant fertilizer. I understand about the nitrogen cycle, I just recently replaced a lot of my filter media (I know it is best not to replace a lot at once but I had neglected replacing it for a while and it was desperately needing to be replaced. I have also added stability to help with the ammonia and nitrites. I've read that thrive can cause a spike in nitrates and I had added the thrive in the morning.

Please confirm your tap water pH as well as your KH and how many hours per day are you injecting CO2?

Yes, Thrive+ contains nitrate so you're either adding too much or not changing enough water per week (or both).
My tap water's pH is about 6.6. I do not know the KH but I will order a test kit so I can figure that out. I have a 120g tank and added 12 pumps of thrive+ which is what it says to dose, I was considering trying less in case that was too much for my plant stock. I had also just done a water change the night before of 50%.
 
Frank the Fish guy
  • #6
If your drop checker is green then you are good to go and should not worry. That is the best way to test the C02 concentration.
 
GlennO
  • #7
What is your usual nitrate reading in the absence of Thrive? If it's usually at or above 20ppm after a weekly 50% water change I would give the Thrive+ a miss and use only micro nutrient fertilisers. Even with decent plant mass, high light and CO2 injection you shouldn't need more than 20ppm nitrates.
 
Shrimpee
  • #8
The key number is the C02 concentration. There is a relationship between pH, KH and C02. You can google it. Too much C02 (> 30 ppm) is toxic to fish. C02 lowers pH. But it is the C02 that harms the fish. They can't breath.

If your pH started at 7.5, and after C02 it is down at 6, then you have too much C02 and may be harming the fish. But we would have to know your normal pH before C02. Changes of more than 1 point are too much usually.

Many of us use a C02 drop checker to keep C02 levels in the 'green zone'.
2nd this. how many bubbles per second is your injection?
once i turn the HOB filter to feed the shrimps. then forgot to turn back on. next morning at about 630 all the shrimps were hanging near the surface and had 4 dead. n my CO2 was on timer to turn on at 5am.
got to off CO2, put in air pump to perch out the CO2.
so if the low ph is due to too much CO2, you should be concerned.
 
courtneylm
  • Thread Starter
  • #9
What is your usual nitrate reading in the absence of Thrive? If it's usually at or above 20ppm after a weekly 50% water change I would give the Thrive+ a miss and use only micro nutrient fertilisers. Even with decent plant mass, high light and CO2 injection you shouldn't need more than 20ppm nitrates.
Usual nitrates are only about 5-10 ppm. I'll try dosing less thrive+ for a bit and see how it goes.
2nd this. how many bubbles per second is your injection?
once i turn the HOB filter to feed the shrimps. then forgot to turn back on. next morning at about 630 all the shrimps were hanging near the surface and had 4 dead. n my CO2 was on timer to turn on at 5am.
got to off CO2, put in air pump to perch out the CO2.
so if the low ph is due to too much CO2, you should be concerned.
My bubble rate is about 2-3 bps. I have an air pump that runs at night once the light turns off (2 hours after co2 turns off) I also have one of my outlets pointed towards the surface to create surface agitation to off gas during the day when the co2 is running. I don't think I have too much co2, I have a drop checker that stays green. I know that's not always a perfect system, but I also keep an eye on my fish behavior. They don't hang out at the surface or gasp, so I'm not really worried about the co2 levels. I will continue to keep an eye on their behavior though to ensure it doesn't become a problem.
 
GlennO
  • #10
What's your method of diffusion? That's a very low bubble rate for 120 gal. Mine is 64 gal and bubble rate per sec is too fast to count accurately.
 
courtneylm
  • Thread Starter
  • #11
What's your method of diffusion? That's a very low bubble rate for 120 gal. Mine is 64 gal and bubble rate per sec is too fast to count accurately.
I'm just guessing on the bubble rate so I may be wrong. The system is off right now and I've been lowering it because of the drop checker beginning to turn yellow. I will check for sure in the morning to see if I can even count it, if not I'll take a video. I have a diy reactor set up
 
Shrimpee
  • #12
courtneylm
  • Thread Starter
  • #13
So here's a video of my bubble count. It seems low to me but our drop checker is green. I may turn it up a hair because the color is a little darker than I think it should be, it's hard to get a good picture because of where it's located (total opposite of where the filter outlet is). My tank is also about empty so that may have something to do with it. I'm filling it today so in the next couple days I'll check it again to see how it looks.



20220419_121436.jpg
 
Frank the Fish guy
  • #14
All looks good to me. Counting bubbles is unreliable since the bubbles have different sizes. ;)Trust your drop checker. Just keep it darker than green. :DNo need to get it bright green. It is easier on the fish to have the lowest amount of C02 that also works for your plants. Green is the maximum.
 
GlennO
  • #15
Yes that's a much slower bubble rate than mine, but I run mine so that the drop checker is a very light green. Also I use a diffuser which wouldn't be as efficient as a reactor.
 
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