Ph swing help

[Irishlad123]

Hi everyone. I have a 100 litre community tank that has been set up for just over a year this week while testing i noticed the ph had dropped from 7.2 to 6.0. I did a immediate water change and it brought it up to 6.6. Its been 6.6 for a few days while my other tank is still at 7.2. I just got a api gh and kh test kit and it took 3 drops in both to change the colour but i dont exactly know what that means. Any help greatly appreciated.

 

[Byron]

This is normal, given your GH and KH. You have very soft water, so its capacity to "buffer" the pH is minimal. Provided you keep only soft water fish species, this is not a problem, quite the opposite, as most soft water fish prefer an acidic ph. Now to simply explain the chemistry.

The GH and KH test of three drops each means the GH is 3 dGH (= 53 ppm) and the KH is 3 dKH (53 ppm). This is very soft water. Only keep soft water fish species, they will thrive.

In an aquarium with fish, organics are continually being produced. As these are broken down by many species of bacteria primarily in the substrate (not the same species of bacteria responsible for nitrification here), carbon dioxide is produced, and CO2 causes carbonic acid in the water. This lowers the pH. In water with a higher GH and KH the increased minerals and carbonates work to "buffer" the pH, keeping it stable. This is more important in tanks of fish requiring moderately hard or harder water with a correspondingly higher (basic, above 7) pH. In tanks with soft watyer fish species, the GH needs to be lower, and this usually means the KH will also be minimal. The pH thus becomes more acidic over time.

Provided you only have soft water fish species, and provided you do absolutely nothing to adjust GH, KH or pH, and provided you perform regular (once a week) significant (50-70% of the tank volume) water changes, and keep the filter well cleaned--you are fine.

My GH and KH is basically zero (actually 7 ppm) out of the tap, so the pH lowers in the tanks to a point that I cannot even test it. It is below 5 in some tanks. Not a problem for soft water fish.

 

[Irishlad123]

Thanks Byron i just taught it was strange because its never happened before if i did want to raise it would i use crushed coral or would u recommend anything else

 

[Byron]

Thanks Byron i just taught it was strange because its never happened before if i did want to raise it would i use crushed coral or would u recommend anything else

Why would you want to raise it??? What fish are in the tank? The GH is much too low for fish requiring moderately hard or harder water, and the only reason to raise the pH would be to match the fish's needs. Soft water fish need soft water, and almost always an acidic pH.

 

[Irishlad123]

Its just that i had been gifted some shrimp that require harder water after them i just have neons corys and a fighter fish

 

[Byron]

Its just that i had been gifted some shrimp that require harder water after them i just have neons corys and a fighter fish

Some shrimp are fine in soft water, some less so. I will leave that for the shrimp experts.

 

[Essjay]

What species of shrimp do you have?

 

[Irishlad123]

Indian zebra shrimp

 

[Essjay]

I've not come acroos those before but google suggests they are Caridina babaulti and need GH between 2 and 8 dH, though whether that is accurate or not I don't know.

You could set up a small tank for the shrimps and add something like this to the water https://www.pro-shrimp.co.uk/salty-shrimp/98-salty-shrimp-shrimp-mineral-ghkh-85g-4260290710478.html

 

[Irishlad123]

Thanks essjay i think i wont keep them for long anyway because to be honest shrimp arent really my thing.

 

[seangee]

Caradina are softwater shrimp and generally require softer water than neos (for which 6dGH is optimal). I would leave it as is. Doing substantial weekly water changes is necessary. pH going low won't hurt them, but if you raise the pH significantly when you do have to do a change it could shock their systems. Regular changes are the key to long term stability.