Increasing KH in my aquarium

[AndyP]

My tap water is kinda funky. The GH levels are 90 ppm. But the KH is almost non-existent.

To raise the KH, I added a bag of aragonite to my Aquaclear filter. And the Aragonite just refused to dissolve. After 3 months. my KH was still VERY LOW. Test kit would immediately go to yellow after only the first drop. My pH was still between 6.4 and 6.8. My next attempt was to use a cuttlebone. I never really noticed a difference in the size of the cuttlebone, and I didn't see the pH really go up.

At this point, I'm wondering if GH has a lot of calcium ions, and that's preventing the cuttlebone or aragonite from dissolving. But whatever the cause, I can't seem to get calcium to dissolve.

So, the backup plan is to just good ol' baking soda. But, one of the problems with using any chemicals to adjust water parameters is that you need to keep doing it after a water change.

So, I'm looking for a calculator that will tell me how much baking soda to add to a given volume of water to get to a certain carbonate hardness.

I'd also like to know if there is a way to test for calcium specifically.

 

[SparkyJones]

KH is a measurement of bicarbonates and carbonates
GH is a measure of total calcium and magnesium

pH should be between 6.8 to 7.4, and never raise or lower it with fish in more than .03 in a shot in a day.

we'd need all measures of the tap water, and all measures of the tank water to see what's going on between the two. are their high nitrates in the tap water? is the tank high nitrates? like if your nitrates are at 10ppm out of the tap, and you are doing 10% or 20% water changes and sticking in 10 ppm nitrates every time, then it's not removing anything, and the fish are adding to it which will lead to OTS, KH dropout and pH decline which won't get corrected by additives, except RO water that is then built up to where you want it.
Are there plants in the tank you expect to use up nitrates or is it plantless?

But all that is another story, test results of all the tap water and tank water parameters would be where to start, see what you are dealing with in both places and the best way to address it so that a buffer will work, or a backing soda adjustment will stick.

I don't think Baking soda is the solution, it might be a temporary fix, but not a problem solver.

there is an API test for saltwater for calcium only for corals. Not sure how it performs with freshwater.

 

[AndyP]

My tap water has about 5 ppm in nitrates. We use chloramine. GH is between 80-100 ppm. KH is between 0-17 ppm. pH is 7.0.

Pretty sure that the KH is way closer to the 0 ppm than 17 ppm. If I use the API test kit and double the water to 10 mL, one drop of solution still goes yellow immediately.

The tank is planted, but not heavily planted. I don't use CO2. I keep the temperature at 78ºF.

Are you saying never raise it more than 0.03 in a day or 0.3 in a day? I can't measure pH to two decimal places.

 

[SparkyJones]

always less than 0.3 pH shift in a day in either direction. more than that can stress and shock the fish and kill them.

1 degree of KH (dKH) is 17.9ppm, assuming it's not zero, but it's 1 dKH or less out of the tap.....
Assuming it's your tap water as the problem and that's it......

The GH is within acceptable range of 70-140, a little on the soft water side but not with a 6.5 pH, so it's not "soft", but not bad it could take some going up, but this isn't of concern really.

what form of argonite are you using? is it like crushed coral? or sand? either way in a filter it's not as effective as it is as a substrate, both are more of a buffer, not necessarily a raiser, both would deplete in 6 months to a year or so and need replacing.

ideally you'd want to add carbons/carbonates to it to raise the KH, maybe get a little more calcium to raise the GH but your test really doesn't show it being necessary. it's in an acceptable range. pH from the tap is 7, very neutral, also a little low, but probably if you bring up the KH, the pH and GH will liven up .

With plants in your tank, I'd look into KH2CO3 or K2CO3 (Potassium Bicarbonate/Potassium Carbonate) this will give you potassium for your plants to use, and the carbonate should raise your KH, and stabilize your pH once your KH is up.

I didn't see the size of the tank.
3.5 grams of KHCO3 in 100 liters of water raises KH by 1 dKH
2.5 grams of K2CO3 in 100 liters of water raises KH by 1 dKH

you really won't get the KH up where you need it to be off of the buffers alone, I suppose you could try some limestone rock formations if you wanted to, (tank full of rock) but I think the best course of action would be to get the potassium carbonate or bicarbonate, whichever is easier for you to get where you are and cheaper, and raise the KH by 1 dKH every day or so, stopping when you get to maybe 6dKH (105-110 KH range) and let the buffer take over from there and see if it drops or then stabilizes until the buffer is depleted.
And you should probably change the argonite if you were at a 1. It wouldn't dissolve necessarily, but it would deplete and just leave the rest behind besides the carbonate, it could be depleted already if KH was near zero.

Your plants will use up the potassium, your tank will use the carbonates, then just water change when you need to for nitrates and treat the water being added with some potassium carbonate/bicarbonate as needed but it's important to follow the formula. it doesn't take much, that like 2.5 or 3.5 grams per 26 gallons of water per 17.9 KH increase.

either version can be found as a food grade supplement powder, and like $10-$15 for a pound. 50 pound bag for a couple hundred dollars or so.

And, yes, other members, if you have a differing opinion, please chime in and voice it. There's more than 1 way to skin a cat, this is just the way I'd do it cost effectively.

I hope this all makes sense, Last thing I want is to confuse you, but I think any other way you'll be chasing your tail and not getting the results you want.

you could use Calcium Carbonate (CaCO3) also a food grade supplement, but I dont' think the GH is low enough to warrant it and if you treat with that it might get your Calcium GH up too high when you bring up the KH. the Potassium is a better more usable by the plants addition for that reason.

 

[AndyP]

It all makes sense. I used to be a research biologist. I've been at this hobby a long time. But the general wisdom for a long time has been to leave it alone when it comes to hardness and not chase water parameters.

Well, that has led to utter ruin in my aquarium hobby on a few occasions. I set up my basement 55 gallon about 5 years ago, and had a MASSIVE pH crash that went from 7.0 to almost 6.0 overnight and lost the whole tank. I woke up and half the fish were dead, and the other half were swimming around like they were drunk. They all died by the end of the day.

The aragonite is just a large bag I bought at the pet store. Not sure the brand. I was under the assumption that I should see the volume of the aragonite decrease. So, I weighed the bag before I put it in the tank the first time, and 3 months later I pulled it out, let it dry and weighed it and it was a whole 1 gram lighter. That made me think that nothing dissolved. And my pH never went above 7.0 and the kH was still 1 dKH or less.

And my tank is a 29 gallon.

 

[Cherryshrimp420]

Aragonite will not dissolve. It's a rock, it will slowly leech out some minerals over time... Same with crushed coral or any calcium carbonate based rock.

If you want to raise KH you can just buy KH buffers from the pet store. But at the end of the day, I would rather just keep fish suited to your tap parameters rather than change it. There are lots of fish that are very comfortable in pH 6!

 

[MacZ]

always less than 0.3 pH shift in a day in either direction. more than that can stress and shock the fish and kill them.

That's very conservative. 1.0pH points in 6-8 hours is possible without a problem, really problematic would be more than that in a short time. 0.3 is not worth mentioninng.

In such soft water I would use an alternative buffering system to KH. Humic substances. Buffers in low pH, which for most fish (except livebearers, rift lake cichlids, rainbowfish) is closer to their natural conditions than raising KH for a stable neutral pH.

 

[SparkyJones]

It all makes sense. I used to be a research biologist. I've been at this hobby a long time. But the general wisdom for a long time has been to leave it alone when it comes to hardness and not chase water parameters.

Well, that has led to utter ruin in my aquarium hobby on a few occasions. I set up my basement 55 gallon about 5 years ago, and had a MASSIVE pH crash that went from 7.0 to almost 6.0 overnight and lost the whole tank. I woke up and half the fish were dead, and the other half were swimming around like they were drunk. They all died by the end of the day.

The aragonite is just a large bag I bought at the pet store. Not sure the brand. I was under the assumption that I should see the volume of the aragonite decrease. So, I weighed the bag before I put it in the tank the first time, and 3 months later I pulled it out, let it dry and weighed it and it was a whole 1 gram lighter. That made me think that nothing dissolved. And my pH never went above 7.0 and the kH was still 1 dKH or less.

And my tank is a 29 gallon.

crushed coral and argonite act as buffers, like in an african cichlid tank, lets say Tanganyikans, you'd want 8.2- 9.3 pH. KH of 120ppm, GH of 180-200 ppm.
you won't get there from 7.2 ph with crushed coral and coral rock or argonite alone, you'd need to raise up the pH and the coral or argonite or whatever used would maintain it up there stabilizing the amendment basically through the buffer, calcium carbonates are slow to react in the sand or gravel form, just trickling a bit, it would need to be a fine powder that could dissolve to get immediate effects from the ppm distribution to the water. but, the pH and GH really isn't your problem, the KH is the problem, so baking soda will raise pH, it will raise KH and GH along with it, but by the time you have the KH up by 100 or so, your pH and GH will be way the heck up there too.

I have a 72g tank, I got really lazy on for a lot of years on that one in particular, the long and short of the story is, it has OTS, my pH is 4, my KH is 0 and GH is 300, My nitrates were above 500.
My tap water is ph 7.6, KH 100, GH75. maybe 1-2 nitrates tops.

I recently looked into methods of trying to turn it around and the fastest most cost effective way is to get rid of all the water and start over, and move the fish with water to a smaller space to be drip acclimated over time to the better conditions. If I mess with one parameter like lowering the nitrates which will start bringing up pH and KH at some point, it opens the door to another parameter going wonky, so it's either baby steps of daily 20% waterchanges for months that do nothing and stil something maybe going wonky, or just drain it and start over and drip acclimate the fish in the sucky water back to good water over time. with a pH under 5, I've got a whole another type of nitrifying bacteria (low pH) that will die off once it starts coming back up. and the ammonia and nitrites will slam into a spike when that happens until a normal pH colony grows.

Anyways, the two situations aren't similar and very different, but so is the approach, and the best solution to resolve them.

your argonite worked, it just can't do what you wanted it to do with that low of a KH, it's an impossible hole for it to fill.

 

[AndyP]

That's very conservative. 1.0pH points in 6-8 hours is possible without a problem, really problematic would be more than that in a short time. 0.3 is not worth mentioninng.

In such soft water I would use an alternative buffering system to KH. Humic substances. Buffers in low pH, which for most fish (except livebearers, rift lake cichlids, rainbowfish) is closer to their natural conditions than raising KH for a stable neutral pH.

I could definitely keep fish than can handle that kind of pH. But I don't like the idea of my pH crashing, which I have had happen more than once.

What specific humic substances are you talking about?

 

[MacZ]

What specific humic substances are you talking about?

The whole cocktail of stuff known colloqually as "tannins"

As I said, they buffer in low pH. True blackwater has no KH, no GH and a pH between 4.5-5.5. Many fish can work with that perfectly.

A pH crash is unlikely in general. If you have measurable KH it can't happen. The higher the KH, the higher the pH. Usually a pH crah is a thing of times when waterchanges were not the norm. The principle is: Without waterchanges and only topping off, the KH goes down, while Nitrates go up. Nitrates are present in water as Nitric acid. So the buffer is lost while acids rise. When KH drops to 0 and Nitrates reach more than 100 it tilts. Result: A true pH crash. e.g. from e.g. 7.5 down to 5 or even 4.
That's a pH crash. If you do regular waterchanges that should never happen.

 

[SparkyJones]

That's very conservative. 1.0pH points in 6-8 hours is possible without a problem, really problematic would be more than that in a short time. 0.3 is not worth mentioninng.

In such soft water I would use an alternative buffering system to KH. Humic substances. Buffers in low pH, which for most fish (except livebearers, rift lake cichlids, rainbowfish) is closer to their natural conditions than raising KH for a stable neutral pH.

I erred on the side of caution, last thing I want is giving advice to play with water parameters and be over optimistic on how it turns out and end up with someone being in a bad spot and fish struggling Maybe too conservative and slow, but a lot of times slow and steady wins the race.

 

[MacZ]

I erred on the side of caution, last thing I want is giving advice to play with water parameters and be over optimistic on how it turns out and end up with someone being in a bad spot and fish struggling Maybe too conservative and slow, but a lot of times slow and steady wins the race.

I'm completely with you. Patience is key. I'm just saying a change of that much, provided it doesn't happen suddenly, is not a problem, if it happens. I would not recommend doing changes like this on purpose.

 

[AndyP]

The whole cocktail of stuff known colloqually as "tannins"

As I said, they buffer in low pH. True blackwater has no KH, no GH and a pH between 4.5-5.5. Many fish can work with that perfectly.

A pH crash is unlikely in general. If you have measurable KH it can't happen. The higher the KH, the higher the pH. Usually a pH crah is a thing of times when waterchanges were not the norm. The principle is: Without waterchanges and only topping off, the KH goes down, while Nitrates go up. Nitrates are present in water as Nitric acid. So the buffer is lost while acids rise. When KH drops to 0 and Nitrates reach more than 100 it tilts. Result: A true pH crash. e.g. from e.g. 7.5 down to 5 or even 4.
That's a pH crash. If you do regular waterchanges that should never happen.

That's my problem. I don't have measurable KH. My API test ki goes yellow after 1 drop of solution. And the alkalinity on my Tetra test strips reads 0.

And I've had pH crashes happen. I lost an entire tank because the pH crashed.

 

[MacZ]

I know, I have read so above. Humic substances REPLACE the KH as a pH-buffer. It will not rise to 7 or so again, though. As I said, it will be between below 6 most likely, but not drob suddenly anymore. Providing humic substances is easier and less costly than trying to keep up KH. And unless you have any hardwater fish, you won't need KH.

 

[Chanyi]

I haven't seen any tank maintenance being discussed - A tank with 0-1dKH, especially planted, is essentially optimal in my eyes. Having a pH in the 6.0-7.0 range and hardly any KH is water the plants love, and most fish do very well in these parameters. As long are there is some sort of replenishment, even a weekly small water change, there should never be a pH crash unless the tank is filthy and loads of organic matter is being decomposed at a rapid rate.

I understand you experienced a pH "crash" earlier, however I think it would be more related to tank maintenance than it would be to KH.

My planted tanks both run below 1dKH. I use 100% RO water, and dose 0.5 degree KH into the one tank (inert substrate) and 0dKH into the other tank (aquasoil buffers pH with acids as MacZ talked about, no need to worry about KH).

I would leave your water alone, instead of worrying about KH and pH, I would:

Ensure there is a quality water change schedule being followed.
Clean out mechanical media / substrate / decaying plants often.
Ensure there is good surface agitation creating lots of gas exchange.

 

[MacZ]

I haven't seen any tank maintenance being discussed

Agree! Now that you say.

aquasoil buffers pH with acids as @MacZ talked about, no need to worry about KH

Correction: I speak explicitly of humic substances (humic, folic, tannic etc acids), not any acids. Important to note that.

Clean out mechanical media / substrate /

Not really. I would try to keep those as full of beneficial microorganisms as possible. Agree to debris of aquatic plants, though.

 

[Chanyi]

Correction: I speak explicitly of humic substances (humic, folic, tannic etc acids), not any acids. Important to note that.

Agreed. I also did not mean any acid. I think those buffering substrate are releasing humic acids thus lowering pH along with up-taking carbonates.

Not really. I would try to keep those as full of beneficial microorganisms as possible. Agree to debris of aquatic plants, though.

I should have specified an over abundance of organic waste. I prefer the least amount of organic material decomposition as possible. I'm not saying sterilize your filter or substrate, I meant get all the waste out of the system before it has a change to produce excess NO3, lower pH and create who knows what else.

It's also worth noting I am not speaking on behalf of blackwater tanks here, I have no experience in that style of tank.

 

[AndyP]

I know, I have read so above. Humic substances REPLACE the KH as a pH-buffer. It will not rise to 7 or so again, though. As I said, it will be between below 6 most likely, but not drob suddenly anymore. Providing humic substances is easier and less costly than trying to keep up KH. And unless you have any hardwater fish, you won't need KH.

For my angefish tank, that will work out well. For the livebearer tank, not so much.

My maintenance schedule is usually doing a 50% water change every 2 weeks.

I don't actively vacuum substrate unless it looks dirty. Plus I am using Flourite Red, which would turn into a disaster if I tried to gravel vac it.

 

[Cherryshrimp420]

If you really want livebearers, what about setting up a new tank with aragonite/crushed coral as substrate? (Not just a bag, you want as much surface area as possible)

 

[MacZ]

It's also worth noting I am not speaking on behalf of blackwater tanks here, I have no experience in that style of tank.

Soil uses the same mechanism, your tank would fall under clearwater I guess.

For my angefish tank, that will work out well. For the livebearer tank, not so much.

Absolutely true. In this case this would at least solve half your problem.

 

[AndyP]

If you really want livebearers, what about setting up a new tank with aragonite/crushed coral as substrate? (Not just a bag, you want as much surface area as possible)

Won't the Aragonite be depleted eventually?

 

[Cherryshrimp420]

Won't the Aragonite be depleted eventually?

It will probably last an entire lifetime