RAFT BED CLEANING! UGH worse than gravel washing

TCLynx

Originally posted over in my farm threadhttp://www.backyardaquaponics.com/forum/viewtopic.php?p=514723#p514723

RAFT BED CLEANING!!!!!!!!!!!

UGH.
I know so many of the proponents of the use raft beds because the gravel will need washing camp spend so much time harping on about having to wash the gravel. BUT they never mention that you have to clean out your raft beds yearly!!!!!!!!!!

I've only ever washed gravel for aquaponics ONCE and never re-washed it after any particular period of time. See there are worms that live in the gravel and if a bed reaches the point of root clogging or even fish poo clogging, I just let the bed rest for a time and let the worms work on it. I've never had to pull all the gravel out to re-wash it. (I've only done that in a duck system and that is just because of all the sand and dirt the ducks and chickens scratched up into the gravel!!!)))))))

Now that I've been running some raft beds for a few years, I've found that about once a year they need a good clean out. I don't believe this is due to solids coming from the fish tanks so much. It seems to be more from what is growing in and falling into the raft beds. My system is outdoors so some leaves and stuff blow into the system. However, probably more problematic is the debris that come directly from the things growing in the rafts and the algae that manages to grow around the edges or in gaps. Plants will naturally have some amount of roots that die off over the growing cycle, some types of plants do this a lot more than others and it will be more severe under different circumstances, these root bits become detritus in the beds and break down. Also, loose media in the net pots or whatever the growing container is will escape into the beds, especially when directly over a bubbler. I don't have too much trouble with escaping media because the peat pellets I use for some plants tend to contain it fairly well and the grow grips don't have loose media to escape. Finally, any leaves from the growing plants that fall often wind up in the beds along with frass or dead bugs. I usually pull my rafts out of the beds to wash them but any operations that leave rafts in place for washing are likely to have even more detritus make it down into the beds.

Eventually all this detritus in the raft beds means you eventually need to do a big clean out and I don't think going much more than a year between clean outs is good.

This is somewhat disruptive to planting/harvesting schedules because it usually means a bed has to go at least a day or so offline so production is likely to take a hit for at least a week if there is more than one bed to do.
Anyway, we do our cleaning during the summer when planting schedules have to be short anyway since lettuce will bolt if left too long and pick a week to start the cleaning operations and we harvest an extra bed to start but don't re-plant it. Once we have a bed empty we get started.
So my method for clean out has been to stick tall stand pipes in the bed to be cleaned and divert flow so it doesn't need to go through that bed for a time. I shut off the air to that bed and pull the air stones to soak in H2O2. I then pump out most of the water from the bed.
Then I start using the big wet/dry shop vac to suck out the rest of the water and gunk.
I have a choice to use the gunky water in the soil beds or wicking beds or I can de-water the gunk to put in the worm bins (the worms love the stuff.) I think I usually have to empty the big vac 4-6 times when cleaning a 4' by 20' raft bed depending on if I need to add any water while cleaning off the sides.

I then have to partially pump down the next bed over and get the air stones back in, move the rafts from the next bed over and finish the switch over of flow so I can pump down the next bed and clean that one.

I've searched for descriptions of how others go about cleaning out raft beds in big operations but have found NOTHING in my searching. I've posted the question a few times and for the most part I've gotten answers like Oh that's how I did it (shop vac) or some vague notion of a modified swimming pool vac without much description of how to manage it. Several people told me to put a drain in the bottom of the raft bed (not sure how that helps, I already have a drain in the bottom, but it goes to the sump so I would just be pumping all the gunk back around the system or I would need to shut down everything in order to run the shop vac just in the sump while the fish are without circulation and filtration. And trying to wash everything into the drain would just mean needing to waste more water to get it done. At least in my system when I'm cleaning the small raft beds I don't loose any water from the system because I can handle that amount of fluctuation. It is only when I have to empty the BIG one that loose water or need a temporary storage location.

Looking for ideas for cleaning. I'm wondering if anyone has come up with an airlift sort of "bed vac"? The idea has been rattling around in my head. I have air lines next to each bed so would be easy on the plumbing part. Maybe something akin to the venturi hand held pool sweeper but without the need to run a hose which would be adding undesirable water into the system. I don't really want to set up another pump that is strong enough to run hose pressure to do the venturi thing without adding extra water (and it means dragging around big heavy hoses for something that is in my experience only marginally effective at removing the fine settled solids.) Only question is would the airlift idea be able to do it any more effectively?

Please play with the ideas!!!!

Colum Black-Byron

There would be a couple ways I'd do it.

The first would be to get into the bed with a big broom, mix it all up into a soupy mess, and then dump the whole bed. But depending on how that's plumbed, it could be tricky.

Second would be to siphon it all out, so have something wide on the siphon, and walk it along the bed, and let gravity suck it all out. It could be pumped into a bucket if you want to reuse the crud, but it makes it trickier.

Or an overly complicated method could be to get a pond pump, put some sort of fines filter (canister filter or something) between the pump and the bed, then loop the water around through the pump backand forth through the bed, and suck up all the solids from the bed.

The one time I've done it so far, I used the whoosh and dump method, it worked well, but wasted water.

thjakits

...how about remove the rafts, let the whole thing settle for an hour or 3 (without any water movement), then pump the water off into a IBC (take it easy to not stir up the muck again....kind of skim it off I guess....)
Then scoop out the muck, rinse the last out the drain (just the very last, should not need much water - good chance to adjust the tub to drain to one spot!!), wipe clean if you care for and pump the water back in from the IBC - done!
NEXT one!

thjakits

scotty435

Hmm, maybe re-suspend the solids using a circulating pump and pump them through a filtration system and then compost them. Re-use the water when you're done. Wouldn't be easy but might be less hassle than getting in there to do it since you could probably leave it to do it's thing while you do something else.

emp1953

I like a combination of two of these. I was wondering how to clean up mine. I'll combine Colum's with thjakits. Stopping circulation, letting the suspended solids settle over a few hours, then use a siphon to drain into the sump when it gets near the end and time to suck up the muck I'll get as much as I can with the siphon into a few buckets and use that in the soil garden. When I get it cleaned out I'll put in another 1" Uniseal with a very short pipe inserted that has holes drilled all around it so next time when I get to the end I can drain the last bits of sludge out that short pipe and use a little extra fresh water to rinse the muck out. I'll put a union on it with a longer pipe that extends above the raft so that it wont drain until I pull the union off.

Tonzz

I can solve the problem

V

V

V

V

dont have raft system... bingo :headbang:

Titus

If you have the space could you not just build an external settling tank.
Flush everything from the raft bed to this. Raft bed now back on line. Deal with settling tank at your leisure.

coachchris

I haven't cleaned mine yet, but will be shortly. My plan is to remove plants and rafts, drop standpipe down and remove most of water to ST, Then when I get down to the last 1" or so, I'll cap off dwc drain, and just drop a sump pump in and pump the water out to dirt beds/garden. Rinse with a hose and that should do it. My bed is small, only 25 sq ft, so it will take longer to remove raft and plants then drain and clean the bed. I could use the bottom water and pump to a settling tank(IBC) but since it should only be 40-50 gallons, it's not really worth the effort. I'll just pump it to close by dirt beds.

TCLynx

Unfortunately my smallest raft beds hold probably 500 gallons of water so I'm not pumping them into an IBC, at least not completely.

I don't have a handy High power pump with filtration system to be able to use the pool vac idea some people have offered up elsewhere.

And the beds are on the ground so siphoning out the gunk doesn't work that well. And draining to a settling tank also has that same problem that I don't have somewhere lower to drain to and pump only get down to the last inch or so of water which usually leaves all the gunk behind so I still wind up using the shop vac.

Right now I'm in the midst of pumping down the 2nd raft bed to get the treatment this year. But with all the rain we got last night I've run out of space for the water, sump is overflowing now. (I had it pumped down last evening but then we got several inches of rain last night.)

Still trying to cobble together some sort of airlift device to maybe suck up the gunkiest stuff without pumping out the bed. I just don't know quite how I should collect the gunk (filter bag will probably let too much fines right back out into the bed while also stirring things up. If I have it pump out into a bucket I'll be emptying the bucket every few minutes.

I have done the shop vac to a mineralization tank before but that entails toting the full shop vac to the tank and dumping it in so I usually save the mineralization tank for cleaning out the filters on the fish tanks since they are up higher.

TCLynx

I was looking at some battery powered swimming pool hand vacuums but they have to be completely submerged in order to suck so I don't know if that would work well in a bed with only 10-12 inches or so of water in it. And again I've heard that they are not that great at capturing the fines or if they are, they clog up very quickly so I would be stopping to clean the dang thing 50 times per raft bed.

I probably just need to figure out how to mount the shop vac head on an IBC tote or something and get some extra long vac hoses. Then just vac directly into the IBC for mineralization and then settling or something. But I probably need several of them then!?!?!?!

coachchris

Wouldn't a small sump pump and a few IBC's be easier? You can pick one up at Rural King for $50.00 and then just pump into 2 IBC's. Then after settling, use the pump to pump back to sump and dump bottom of IBC's into dirt beds via the same hose. The 50' x 1.5" blue flex hoses are around $10.00. You can hose clamp a female hose end if you wanted to use a watering type shower nozzle to water dirt gardens with. I like having at least 1 sump pump around as a backup for my AP system. It won't work for ever, but it would work for a day or so, til I got my new pump online. I use it to suck out the bottom few inches in my shade cloth/netting filter in the RAS. I drain out most to the MT tanks, then pull out the netting and then rinse everything down and throw the sump pump in. A few more quick rinses and the tank is clean. I still have to clean all the crap out of the shade cloth and netting, but the tank part is quick & easy.

Ryan

My setup is fairly simple... I turn off the air then use a high volume pool pump with a vacuum head and have it attached to a 150' flex hose. I vac the troughs into my mineralization tank, clean water goes back in the trough. Takes me less than a day to do near 400' of troughs.

Not very hard if you have the right equipment

TCLynx

yea Ryan thanks for the info, that might have to be on my agenda for next year. The high power pool pump to run a pool vac is what I'm lacking at the moment.

Simply pumping out the trough using any sort of pump is going to leave behind quite a bit of sediment and gunk since most pumps can't take the water level down to 0" That wet sediment/gunk is what I'm having to shop vac out along with the last inch of water.

My Lufa are loving getting all the gunky water from the process though.

TCLynx

Ryan wrote:

My setup is fairly simple... I turn off the air then use a high volume pool pump with a vacuum head and have it attached to a 150' flex hose. I vac the troughs into my mineralization tank, clean water goes back in the trough. Takes me less than a day to do near 400' of troughs.

Not very hard if you have the right equipment

How do you mange this without overwhelming your mineralization tank with the high volume of water coming from the pool pump vacuum?

MasterCATZ

This actually has me thinking
I might even put an under gravel system in my raft systems
and while running an airstone make use of it as part of an bio filter
( at least this way the gunk is pulled under the gravel and bacteria can break it down more )

any plants that can be grown as fish food on the bottom ? without light source

or just let the Raft plant roots penetrate the gravel and hope they remove that gunk build up one day

I must admit I used to just let my undergravel sets keep running when I was being an aquarist enthusiast
every so and so I would reverse the flow just to give the poop down below a mix to help dislodge
so I could skim excess out of the system
but whatever was breeding under the gravel was definitely doings its job I remember some tube like worm things I could see sometimes through the glass walls

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