20 POND MYTHS EXPOSED:Myth 2 -The presence of rocks and gravel make it difficult to clean a pond. You are susceptible to buying into this myth if, and only if, you've never experienced pondering with rocks and gravel in your pond. if you have a smooth-bottom pond, and each season you're amazed at the amount of muck and grime that collects on the bottom, you automatically rule out rocks as a solution. You keep visualizing that same amount of muck on top of the rocks and gravel and say, "NO!" to even considering them. ; It's understandable. it seems logical . . . until you learn the rest of the story.

Rocks and gravel offer a natural place for aerobic bacteria to colonize and set up housekeeping. this bacteria breaks down the fish waste and debris that would otherwise accumulate in the pond and turn into sludge. Regardless of your pond's location (i.e., close to trees and loads of leaves), or how many fish you have in it, you'll find that having rocks and gravel in your pond not only makes it look better, but it makes it healthier, as well.

So, contrary to the myth, having rocks and gravel on the bottom of your pond actually allows Mother Nature to clean up after herself, saving you headaches and hours of work trying to keep the bottom of your pond muck-free.

Oh, just had a little thought about your system. You might want to plumb some bottom drains from your tanks down to the sump so that if you need to drain one of the tanks, it will be easier than having to lug a submersible pump in to the tank and run the hose out somewhere. This might be easier to deal with using simple valves for when you need to harvest fish (would be tricky in a 2 meter deep tank) or if you need to remove said rocks or do other repairs.

I have tried rocks in my small AP bathtub, they just let a whole heap of gunk build up. It does give you more surface area for bacteria (thats how aquariums work), but it makes a big mess when you move them later.

I would place the rocks into a crate of some sort, so they can be stopped from spreading all over the tank.

Would the plants growing in the fishpond be using the same nutrients as the ones you want in your growbeds?

Rather than using gravel and rocks for fish hides maybe something larger like pipe offcuts would achieve the same goal. In AP don't we want all the muck to end up in the growbeds?

Hmmm. I have rocks in the FT of my barrelponics system. That's the one with the gunk buildup... Time for some cleanup!

but there must have been a reason you put them there in the first place.