Do I need to add trace elements to Rain Water?
I have access only to rainwater, therefore all my tanks are straight rainwater. Natural rainwater tests at below 6 ph on my test kit. I just purchased a GH and KH test kit, and the instructions say count how many drops it takes to change the liquid to a certain colour. Well, the first drop changed the water from clear to the appropriate colour which if I understand correctly means the GH and KH measures 0-1 dKH or under 17.9 ppm GH/KH. I have a couple of questions, which go hand in hand really:
1) given these natural water parameters, presumably also lacking in certain elements and minerals fish would normally have, what do I need to add back to my water to maintain good fish health for my 5 foot tank - (setting up next week) inhabitants will eventually be schools of tetras (cardinal, rummynose, maybe embers) and also sterbai corys and a few bristlenose. There will be plenty of driftwood in the tank which is chucking out tannins galore (so I'll be using a bag of purigen in the filter just so I can see the fish lol) and it'll be heavily planted. Would dosing the water with seachem fresh trace be advantageous? Or is there a diy combo I can makeup?
2)Until just recently, I used to keep african cichlids, and used a diy mix of bicarb soda and epsom salts together with coral in the filter to effectively buffer the water. That kept it consistently at 8 ph. This time round for my tropicals, I'm wondering how best to buffer the water naturally to keep it at about neutral or just below without using ph up all the time. My understanding of GH and KH in general is not great, but from what I've read when keeping tanks at a ph below 7, without sufficient KH, ph swings are very likely. I don't want to crash my tank, I want to keep it stable. Would adding a small amount of coral in a mesh bag be worth trying, monitoring the ph over a couple of weeks to check it doesn't raise too high? I'm using MTS capped with fine gravel, and will be sprinkling some dolomite underneath everything, so once it's up and running I'll test the water first, ph may be acceptably raised from the dolomite, but I'm assuming the dolomite won't last forever.
Sorry for the long post, your insight would be appreciated.