Aquarium ph and filter question

[Jxoke1983]

hi people, I’m gonna use a 40 breeder divided in half and I am wondering what the best way to lower ph besides a reverse osmosis filter. And if you think a sponge filter on each side of the divider would filter it well. It will be an Apistogramma breeding tank so I want best conditions for them.

 

[Byron]

The pH is relative to the GH and KH. Adjusting pH needs to involve the GH and KH. Do you know the values?

 

[Jxoke1983]

The gh Is 72.6mg/l according to my water provider. how do I find kh?

 

[Byron]

The gh Is 72.6mg/l according to my water provider. how do I find kh?

KH is carbonate hardness, sometimes termed Alkalinity. It is usually similar to GH, by which I mean if the GH is low the KH is also low (there are as always exceptions). The GH here is 72.6 mg/l, and mg/l is the same as ppm which is one unit we use in the hobby. The other is degrees, and 72.6 ppm is equivalent to 4 dGH so this is soft water, close to being very soft. The KH which is the pH buffering capability is likely to be similarly low. This buffering capacity is what prevents the pH from fluctuating. If you try to lower the pH, the buffering capacity will work against this, which is why attempts to adjust pH can be so deadly. Fish can often manage with a pH that is stable even if not exactly in their preferred range, but fluctuating pH can weaken them seriously, and eventually kill them. And if the aquarist continues to attempt lowering the pH, at some point the buffering capacity will be exhausted and the pH can then crash.

You didn't give me the pH of the source water or the tank water. As organics accumulate in every aquarium, the breakdown of these by various bacteria (primarily in the substrate) produces CO2 which in turn produces carbonic acid and the pH naturally lowers. The buffering by the GH/KH may or may not block this, depending upon the factors. This is why any adjustment of the pH must consider the GH/KH first. Reducing (lowering) the GH and KH will allow the pH to lower naturally. But you/we need to know the pH of the source water and the tank water, separately.