hard water

Do Bichir prefer soft, medium or hard water with what ideal PH? I was thinking 3-6Kh with a Ph around 7-7.5? But all comments appreciated.

I’m cleaning up a tank for a friend of mine and am going to paint the back. The only problem is is that there are hard water stains on the back. If I paint the back will the hard water stains mess up the paint?

So I've got a little 29 gal, a whole load of crushed coral sand, and loads of coral skeletons sitting around doing nothing. I'd like to plop the sand and dead coral into a tank, and i plan to keep the aquarium freshwater or maybe brackish. I could do with a little advice on stocking said tank...

Hello, I have a 6gal Fluval edge that is currently salt. Previously it housed a fire shrimp for 2 year. I am debating on switching to a freshwater tank for crystal red shrimp. I have a couple of questions though: 1. the pH of the water here is 7.8...would the shrimp survive even with drip...