Connswater
Member
Thanks for reading my post Maverick. It is not really the case that we need soft water, if you haven't seen it, try and get a copy of Karen Randall's Sunken Gardens, it is not a technical read, I'm not a scientist and I think it is very well written, danios, barbs, goldfish, live bearers, and most cichlids all generally thrive in hard water, sometimes very hard water. Karen is an American plant expert and illustrates some lovely hard water planted tanks.
Hornwort, some crypts, some Amazon swords, hygrophila polysperma, Egeria, Vallis all thrive in hard water. Hornwort doesn't do nearly as well in soft water. In very hard water it grows well but does take on a brittle nature.
A low pH is not important in and of itself for most fish or plants. There are some tetras who need very soft water, but they still only need a pH around 6-6.5 even to breed.
As others have written, we generally aim to have a lowish KH not GH and a neurtral pH. RO water is simply water pushed through an ultra fine filter to remove all salts, it needs to be remineralised or blended with unadulterated tap water to make it safe.
You must know what your tap water is in GH and especially KH. You have to know the baseline. I grew up in a soft water area and kept fish, without doing anything to my water, then I lived in a hard water area and kept fish and grew a good range of plants without doing anything to my water. If it is safe from the tap to drink, give or take the odd chlorine addition from the water company to kill bacteria, it is fine for fish and plants.
Then, decide what type of plants you want to grow and what type of fish and then, aim for a target range. The vast majority of folks with planted fish tanks do not change the mineral levels of their water. The pH changes a little itself because of processes in the tank, pH normally falls at night - plants give CO2 - and rises during the day - as plants give O2 , as in a lake.
As I said earlier, just mixing in chemicals will do no good without knowing what you have and what you want to have in terms of KH.
Adding lots of bottled fertiliser, will lead to really high Nitrate and particularly really high Phosphate levels and these are not going to help the plants.
Think of all these things like blood sugar levels, you could easily turn a tank into a sort of equivalent of a type 2 diabetic.
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