So I'm looking to increase the pH of all my tanks, and someone here suggested crushed coral aragonite sand (same thing, right?). I'm looking on ebay right now and there's quite a few options, however, before I buy anything, I have a few questions.
How much of it do I need to add? The tanks are 3 gal, 6 gal and 15 gal. All are sitting at around 6 pH, I want to increase the first two to about 6.7 and the last to about 7.5.
Is it safe? All the listings say it's "marine"; nothing about fresh water :/ I'm worried about it altering my water too much.
Edit: what size would be best? I can get anything between 1 and 5 mm. Smaller tanks are in the process of getting switched from gravel to soil, so I'm not sure if I could just use the sand as a cap or not. 15 gal is bare bottom, so I'll just put it in a container and keep that in the tank so it doesn't go everywhere.
Should I just take all my fish out, add the sand and acclimate everyone? Or should I add the sand gradually instead? I think it's worth noting that all fish but one are fine with getting cupped.
I'd really appreciate some help and advice on this. Thanks to everyone in advance.