Backyard Aquaponics
A place to discuss aquaponics

My grow beds are filled with gravel that has a lot of limestone in it. It's pushing my pH up to 8.5+ and my plants don't grow because all the nutrients they aren't getting. I was going to replace it with new gravel that doesn't have limestone in it, but then I saw someone selling crushed granite. I know granite contains a lot of trace elements that plants love, but would it be safe for my aquaponics system?

They seem to use granite in aquariums so I assume it's fish safe.

Do you think it'll "gum" up my pipes and pump? Are the trace elements in granite available for the plants to take up? Any other foreseeable problems?

Granite is very hard, maybe it won't dissolve much at all.

I expect granite would be fine provided it is the proper size. You probably won't gain much in trace elements from it but certainly better than the limestone. Just make sure it hasn't been sprayed with anything that would be bad for fish (sometimes gravel for use in roads might be contaminated with oil or other stuff that could be spilled on it.)