Cleaning Media Post-Harvest

[AJ Grottke]

My question is geared towards people who use reusable media in net pots either in NFT or DWC.  I was wondering what other people do with the media (ex. hydroton) and net pot after harvest?  Do you pull the plant and whatever roots out that you can and then put it back into the system for reuse, leaving some old roots in there?  Or should the media and net pots be rinsed and cleaned/sterilized like hydroponics?  I just harvested my first batch of plants from NFT; i just pulled the plants out and put the net cups back into the system uncleaned.  Im am curious over the long run how the build-up of small  roots and other organic debris affects plants growth and health of the recirculating system.

[TCLynx]

I think most commercial operations will clean the net pots and rafts between plantings.  And if they use reusable media, they probably will clean those too.  I think friendlies uses hydrogen peroxide for cleaning and others might use a very weak bleach solution.

 

for home use provided no disease have caused problems you might get away with simply rinsing the net pots, rafts and media before re-planting.

[Kobus Jooste]

I use gravel and perlite in pots.  I re-use the gravel after a rinse, and rinse off the pots, then leave them out in the sun for a couple of days.  I have surplus thus pots seldom go straight back.  I have found that with the lighter media, like perlite, it is too difficult to get it recycled - trying to get it all out of the roots, thus I am reverting totally to finer (10 mm - 13 mm) gravel to see how that goes.

[AJ Grottke]

Thanks for the replies :)

Yeah TC, I always used an H202 soak for my hydroton and pots in hydroponics, followed by a debris rinse.  I will probably stick to this regime. 

 

So the undersides of the rafts are cleaned after harvest, makes sense, what do you all think about the actual NFT channels needing to be cleaned?  Every harvest, every 6 months, every year?  Also in hydroponics i would always use a enzyme product for the first few weeks of growing with reused media.  The enzymes supposedly break down old organic materials (root hairs) into nutrients.  What are peoples thoughts on an enzyme product in the system (effects on fish)?

[LogicalHydro]

Are you talking about an enzyme like AN's sensizym? I have used this product and seen good results. I can't see it being super harmful to the fish in small doses. But a dose large enough to make a big difference might be fatal.

 

One thing I hate doing is cleaning hydroton, especially from net pots. But I have found H2O2 as an effective method as well.

[TCLynx]

many people are using coir in their net pots and I expect they are composting the used media and starting fresh for the seeds each time.

[Ricky Flickenger]

This is just a thought (I currently have a system where things are permanently panted and I don't have to harvest and clean the media, but I'm installing a grow tower with hydroton in the coming weeks and was wondering this myself) After harvest can't the old roots just be left in the media with the water still flowing to be broken down by bacteria & worms (if you are using them) to be used by other plants in your system?  Some turning over of media might be needed occasionally, but I would thing in a mature system it would be broken down fairly quickly and you could replant again.  Plus, if you clean the media, don't you lose an enormous amount of bacteria in the system?

 

This thought is assuming that 1) there ARE other plants in your system between crops, like I mentioned, my has 1 large and 2 small permanent plant filters that clean the tank, and 2) you are growing in an area that can be replanted not to long after like inside or a greenhouse.

 

Like I said, these are just thoughts - not really sure about the logistics of it.

[TCLynx]

The physical nature of the tower is going to affect the replanting of the tower.  Seems to me a challenge to replant a gravel kind of pocket tower with say strawberry plants without dumping the media out and starting again.  But perhaps seeds would be a different story and this will all be dependent on the tower type and the way water flows in it and if worms can move in it.

Zipgrow towers you can take down and re-plant pretty easily without cleaning the media.  I've never cleaned it yet at least.

 

Cleaning the media.  If you were to gently swish your media in system water to kinda rinse it a bit, you probably wouldn't loose all your bio-filter bacteria but I expect removing all the plants from a bed and disturbing all the media and exposing it to light as you go would set your bio-filter back a little, don't do all the beds at once anyway.  I don't see any need to do it in the first place as long as you have enough media to handle the system and the worms to work as the cleaning crew.