Cleaning media/rafts between uses

swanberg

Hi all;

My setup is a pretty standard 2" insulation-based raft trough system, using gravel as my media.
My question is for those who are using rafts, and re-usable media like gravel.

Do you clean and/or sterilize your rafts and media between uses?

How?

I could see setting up a rack of some kind with a tub under it, and then spraying the rafts with a water/hydrogen peroxide mix, or a tray big enough to lie a raft down, and soaking them in a hydrogen peroxide solution for a few minutes, and then hanging them up to dry. Does anyone do anything like this, or do you just spray/scrub them clean with water?

For gravel, I could see again spraying a hydrogen peroxide solution on it, or, and I really like this idea for no good reason, building essentially a tumbling composter. Get a blue barrel, hang it horizontally on a bar, drill holes in the sides, and then rolling gravel it in while spraying hydrogen peroxide, etc.

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Or, I could see sending all the gravel through a worm bin, but that would be very labor intensive.

Ryan

I don't scrub the bottoms of the rafts (to keep the bacteria thriving in place) and use a soft bristle deck brush for the tops of the rafts after harvest. If they are really gunked up I take them out and spray them off, then scrub. if they just have a few stains from dead lower leaves I push the raft down into the water column to get some water on it and scrub it in place. Just make sure it has soft bristles.

The only thing I sterlilze are my net pots and my scissors. If I did happen to have some big outbreak of disease I might try something more extensive but Ive never had that happen. Hope this helps!

swanberg

Thanks, Ryan.
How do you sterilize your net pots?

Ryan

I use a mild (1:10) bleach/water solution. Just make sure to mix it in a well ventilated area and soak them for a couple hours

pancakes

My one buddy bought a concrete mixer then drilled holes in it for hydroton cleaning. It worked but dumping it in then running the pressure washer into it to get roots and organic stuff off the hydroton/shale/lavarock was labor intensive. This was for hydroponics but after a while of doing it I filled the ebb and flo tables full of media then would grab out rootballs toss the hydroton in the mixer to pressure wash but left the majority in the growbed. I used hygrozyme but don't know if its OK in AP use to prevent root rot as I started leaving tons of dead roots in the beds after a while but the hygrozyme seemed to work well as I never saw root rot in those beds so we started doing to to more.

I would never bother to clean any of it now except whats stuck to the plant you pull out then the pressure washer+ concrete mixer was a-OK. I would not bother with h202 or bleach as killing all bacteria back allows other non-beneficial to grow back faster then the good ones in my opinion as that would happen in my mycological experience where over sterilization of a substrate would cause later contamination over regular pasteurization leaving beneficial colonies intact that could be overtaken by your target organism. It is amateur experience so take it with a grain of salt as I do not know if it would cross over to media. If we had root rot we would just dump the media in the creek or it would become driveway gravel.

As for cleaning rafts and netpots has anyone ever made raft netpot combos? I have seen rafts with holes that fit root cube starters for lettuce but non that hold media as well. It would super simplify cleanup to get some or make some plus the fiberglass or plastic they would be made up would clean easier plus be more durable. But is it a good idea to clean the biofilm off rafts? I thought it was a good place for more nitrobacters?

If I was to sterilize net pots I would autoclave them after cleaning them of organic bits. The bleach soak sounds good for a sanitize soak but I know h2o2 destroys the heck out of root rot on porous organic surfaces. What about a restaurant style dishwasher where you slide the racks of them in, drop the doors and it cleans in a few minutes IIRC they are pricey but in a high volume operation plus a used one probably being cheap(1k for a used one that was 4k) it could be an option but finding a way to just not use net pots would be my goal with rafts.

sorry about the long post but I have cleaned tons of media for hydro before and its such a pain I tried to find ways just not to do it and just wanted to share.

scotty435

If you're not planning on sterilizing the entire channel and the board I doubt sterilizing the net pots will help much.

I could see cleaning most of the pots but if you cull any diseased or stunted plants definitely sterilize these pots with bleach. For most pots though you are probably good if you just get them clean and remove any salt deposits. Running pots through a dishwasher as suggested might work for most. This can be hard on some plastics (I'm not sure about net pots).

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