Jayzao;4397609; said:
Thanks for the great info.
The water hardness has been pretty well maintained (by way of test strip) as I have quite a few natural rocks from the yard. But the information about the depletion due to RO makes perfect sense similar to humans drinking too much distilled water and becoming Hypervolemic hyponatremia candidates.
PH has remained stable, but high due to rocks and crustacean population but I will continue to test and start changing water using the tap.
My main concern with tap water was chlorine. Should I use a water treatment in addition?
Use dechlorinator.
I use API dechlor, but I've also used stress coat, prime and several others. Prime detoxifies nitrites and ammonia and can remove nitrates to an extent, but it smells really bad, so that's why I use API.
Calcium carbonate based rocks (like limestone) will maintain hardness and alkalinity to an extent, but put in pure RO they probably won't dissolve fast enough to keep the hardness and alkalinity up high enough. Plus your fish do need more than just calcium and carbonates.
I would also recommend finding a liquid test kit (I use API) to test alkalinity, hardness, and pH, because the strips are notoriously inaccurate. Really the strips are not trustworthy for most tests (ammonia, nitrites, nitrates etc) because they will degrade when sitting on the shelf, after opened, and can be faulty directly from the factory for that matter due to mishandling.
You can use RO water if you get something like Kent Marine RO Right to add the hardness and electrolytes back into the water. They also make something for alkalinity, but you can really use baking soda (being sodium bicarbonate it will raise your alkalinity (due to the bicarbonate) but not the hardness) , along with limestone based rocks in the aquarium.