Raising Carbonate Hardness

[Trebs]

I'm really getting sick of my ph crashing due to low kh. I do do a lot of w/c but my fish load and the low kh out of the tap means this keeps happening.

What are the best methods for raising kh? (preferably natural).

My KH out of the tap is about 2-3 degrees (not sure what this is in ppm - will check and update my post) and lower in the tank. At what level should I aim to keep my KH to keep PH stable? Ideally I'd like to keep my PH stable somewhere between 6.5-7.

Thanks.

[lesley]

Hello Trebs,

Calcium Chloride, Calcium Sulphate (Gypsum) and Bicarb soda will help your carbonate hardness. You will find that the first two do not affect the pH much but do not raise the carbonate hardness as much as bicarb soda.
Bicarb soda does raise the pH so if you are going to use that, you will need to experiment. You will also find that carbonate raised by bicarb soda gets used up quickly. I run my tanks on on a kH of about 2-3, but you do need to keep an eye on that pH!

The first two are best used in liquid form Ca.chloride (Stopit or Pitstop, agricultural chemicals for calcium deficiencies) and Ca.sulphate (Gypflo, another calcium supplement).

Calcium carbonate will raise your carbonate hardness a little, but also raises the general hardness.

HTH, Lesley

[Trebs]

Thanks for the reply. I'll have to have a go at that.

I was kinda hoping there would be a way for me to adjust the KH to about 5-6 without instantly changing the PH (obviously the increased buffering capacity will effect the PH over a short period of time).

[Dave76]

You can try adding some limestone or crushed coral to increase the KH - it will effect your PH, by how much depends on how much you add.

It might pay to experiment on a spare tank or tub of water first and go from there.

In my cichlid tanks the PH raises by .1 or .2 for each 3-5 of KH.

Hope this helps

Dave

[Trebs]

I have a bag of crushed coral (pieces are 2-3cm in diameter). I'll try it on one of my tanks and hopefully get an idea for how much to use once I get the new system in place. I'll try that and post my results.

[Trebs]

I've done some additional reading namely in planted tank and african cichlids sites. They are suggesting the same sorts of things which is good to hear. I now have a much clearer idea of how to proceed.

Thanks everybody.

I'll post my results as I go along.

[Trebs]

I added about 3 teaspoons of baking soda to my 90gal. The KH was raised from 1 degree to 3 degrees. The ph came up quickly from <6 to 7.2. I removed so fish to reduce the bioload. I now have 2 pairs in the tank which are currently breeding. It's been 4 days and the kh and ph are both constant at 3 and 7.2 respectively.

[Aurora]

You can buy kH powder that will set the pH to a certain value. I brought kH powder 7.0 which increases the kH and brings the pH to 7.0. I have also seen 6.5

This is good because you dont have to worry about adding too much and sending the pH too high. It also means the pH will always be constantly 7.0, whereas if you are adding something else that happened to get it to 7.2, it might not be the same the next time you add it.

[Trebs]

I don't want to touch buffers. All you really need is a good water ager and a good understanding of water chemistry.

[lesley]

Hi Trebs,

I found the when I was learning what went best that the couple of buffers I tried were disastrous. I now have a basic mix of the previously mentioned ingredients that I add in small amounts and watch the fish for any necessary minute adjustments. You will be finding that you can't add much carbonate hardness without raising the pH!! Which is not really surprising, if after all, carbonate hardness is alkalinity, from my basic understanding.

I manage to run mine now at just under 7 and still maintain enough carbonates for the fish and plants to be happy and the water stable. I am also using crushed bentonite which I believe might be helping to stabilise as well - the jury is still out on that one.

Lesley