Backyard Aquaponics
A place to discuss aquaponics

Ok so I followed ruperts advice picked up a bag of cat litter and it seems like a good medium, it doesn't dissolve, it sinks, its hard and absorbs water, BUT its too fine. It'll get through drain screens and the such and make a mess. Too bad its not like 3 times bigger.

So here are my options right now.
1. blue gravel
2. white gravel
3. cinder (red or black)

I can't seem to find anything else. I'm leaning toward the cinder since its lighter than the others. What so you guys think? Advice? THoughts? experiences? Other ideas?

We're going to run a 300gal pond with 2 8'x2'x1' growbeds.

HN

Suspected that it might be like Perlite... either float (which it doesn't) or be too fine...

Try mixing it with Vermiculite in a 75:25 Vermiculite:Litter ratio..... should make it managable...

How coarse is the vermiculite you're thinking of? The only one I've seen available here is finer than the kitty litter and it floats. Arghh I hate lving on an island sometimes....

Humm.. vermiculite doesn't normally float.....

There are various gradings of the stuff... right up to quite coarse....

Sounds like you'd have to screen your outlets...

Other option ... if you want to use the "litter" that you've got... would be to mix it with some of another media type...

But if your only other chices are gravel/scoria... then it's probably just as easy to leave it out...

Three factors I like are light weight, smooth rather than sharp for easy hand work (and not puncturing liners I use), and size (about 1/2" or 12mm is really nice). I tried cinder & liked the weight, disliked the sharpness and found roots really clung to it rather than pulling loose.. Now I'm using some more expensive river rock (somewhat rounded), but much heavier.

Tradeoffs: hrmph! It makes my head spin.

Rupert, see I hate hawaii, even our vermiculite is screwed up. Sheesh.

Hydro, thanks for making it even harder to choose. Haha, nah thanks for the input. Great things to consider. I like cinder's weight also.

HN

You can place gravel (or cinder or whatever) around drainage points etc to stop litter getting in, then fill 'er up. This is what Monya did with the perlite beds in my system (plus 5cm of gravel over the top to stop it floating, which you probably won't need).

Cinder sounds like what some aussies call scoria.

+1 for surrounding the pipes with cinder, then mixing the rest of the vermiculite / media together with cinder.

I'm curious about using cat litter as a grow medium. Would it drain enough for the roots to get the air they need? It seems to me like it would be too dense and would stay too wet.

Hawaii. Got coconut's over there. I thought someone used coco peat but found it was not chunky enough. Cutting up the husk you could make it very chunky but I don't know how it would go in a GB. Maybe more suited to a drip system. Do you want it mainly for the GB or is it the Bio filter part. And how big a system are we looking at. I made a bio filter with 13mm tube and river rock. Later I can use this before a NFT system. Never thought of using it as a GB until now.

What sizes can you get the different gravel and cinder in?
Is the cinder like lava rock?

I've used the big red lava rock around the drain pipes in my grow beds. If I couldn't find anything else but could get decent priced 1/4-1/2 inch lava rock, I would definitely be willing to use it. It is light weight which is nice. Provides lots of surface area for bacteria! Only drawbacks I see with it, it would be tough on the hands to dig in and the roots would tend to pull lots of it out of the bed when removing plants.

isn't cat litter made of clay?

I'm using chunks of coco husks, it brings down the PH, so you'll have to balance that. For this I use shells. You could try coco husks mixed with shells, with the bottom mainly being shells to help with the drainage.

While I'm new to aquaponics, I've had great results with coco coir in soil gardening. This media has a lot of potential with many advantages such as:
- high cation exchange capacity.
- contains potassium, phosphorous and other minerals
- lightweight
- environmentally friendly as it is a sustainable waste product

One of the disadvantages is that it turns the water brown, which is irritating. This improves with water changes, but it takes a while. It may be expensive in your area. I'm in Thailand where it's dirt cheap, a huge sack is less than $3 and it's much cheaper if I buy a truckload.

Any benefits or detriments to using crushed fired building bricks?

Another thought is walnut shells or shells of any other hard nut) - maybe even coconut shells crushed in a mill.

Maybe rice hulls or sunflower shells could be worth a try. They take considerable time to rot.