Peat moss as a medium

[momofboys]

I've just switched my barrelponics system over from gravel ebb and flow to raft with net pots. I planted out 6 of the 8 growbeds yesterday with peat moss as a medium.

But then last night I read in my Friendly Aquaponics manual that they recommended using coconut coir because peat tends to harbor mold and fungi.

Has anyone used peat before in a flow-through system? Any good/bad experience to share?

I can switch over to coconut coir , but all the work of yesterday will be wasted, as well as all those nice seeds...

Thanks,
Michelle

[arachdog]

Personally I wouldn't use anything organic. Anything that susceptible to decomposition is only going to increase your BOD. If I had to choose from those two then I would go the choir since its supposed to naturally resistant to molds etc. But if had freedom of choice, then I think I would choose rockwool.

[momofboys]

Thanks, what's BOD?

[arachdog]

Thanks, what's BOD?
Biological Oxygen Demand
It means that anything living (in this case it would be 'bad' decomposing bacteria living on the moss\choir) that takes oxygen out of the water. Its best reduce it where you can because your fish, your growbed and your bio-filter if you've got one, need that oxygen

[momofboys]

Okay, but doesn't the grow medium act as a biological filter? I don't have any other filter in my system. I only have airstones in the FT, but it's way overkill, with VERY high DO, then the water falls several feet into the dump tank, and again flows down a long gutter and falls again into the sump tank, so it gets more aeration that way.

I'm not sure how I'd incorporate rockwool into my system of foam rafts with holes drilled for net pots.

Thanks,
Michelle

[arachdog]

Well to be honest I've never seen a raft system. What what others have said I gather it basically a big sheet of styrofoam floating in a tank with holes cut in it with little plastic baskets sitting in the holes. So I would have thought you just stick you seed in the rockwool, and drop it in the basket, but I could be missing something. Perhaps you are talking about net pots actually made from moss\choir ?

I've got no idea how big the 'net pots' are so I'm sure how significant a role they play, but I always assumed its mainly the plant roots that provide the surface area for bio-filtration in a system such as this. Which kind of makes proper management of the bed essential.

[momofboys]

When I searched online for rock wool, the pics I found made it appear to be quite solid, not loose or malleable, so I wasn't sure how it would fit in the plastic net pots (2" and 3" diameters).

I'll have to check out the rock wool the next time I visit the hydroponics store down the road. I try not to go too often because I always end up buying something I didn't realize I 'needed'.

Since Friendly Aquaponics uses coconut coir exclusively in their commercial beds, I'm guessing it'll be fine. Right now, I have a little experiment going--6 growbeds are planted out in peat, 2 are planted in coconut coir. I guess I'll just watch the seedlings and see how they do. That, and keep checking the DO--I was vague on that because my DO meter is on the way. :)

I'll post photos at a later time of our system--a barrelponics converted to raft set-up.

~Michelle

[arachdog]

You can buy loose chunks but generally every plant gets its own solid chunk. But yeah you probably should go with coconut choir. Rockwool is probably better, but quite a bit more expensive, especially if your pots are that big.

[Ravnis]

one issue you may have more with peat than coir is ph drop. Peat has been added to systems to drop the ph in high ph systems (>7.4). Since you would have to loose your seeds and your labor, you might be best to see what happens in your climate. Isn't Austin a pretty warm and dry climate?


The rockwool cubes should be able to be dropped into the net pots and used that way. You could use a little hydroton or gravel to provide additional support. I used hydroton when I was playing with 2 and 3" net pots in a pvc NFT system. I tried the coco coir and decided against it as it would break loose and clog my pump. You may have something in your design that overcomes this issue.

[urbanrunoff]

hello i'm new...
i use peat moss as media in a shallow riverbed/constant flow system.
I have issues with high pH from my water so i thought peat moss might help. I use net pots then some peat moss with plant and cover the top with rocks to avoid fungus gnats. Works great with my salads.
And i think peat moss helps to retain some nutrients when adding some fertilizers.

[GaryD]

Hi,

One of the advantages of using coco coir (as distinct from peat moss) is that coco is Pythium-free.

A 60:40 mix of coco and vermiculite is a good growing mix.

Gary