A Simple System

[Larry]

This is my 1st system and its been fun getting here. Still a lot to learn.

I'm using a 140 gallon feed tub as a FT and 4- 2 x 3 ft mixing trays as GB's. The media is cinder(lava), there's a lot of that here in Hawaii.

I've ganged the 4 GB together with 2" PVC with drains at the bottom. The drains are 2" shower drains. The system completes with an external siphon dumping back into the FT. The system cycles every 15 minutes and hasn't missed a beat for 2 weeks now(knock on wood).

I'm about done with the fishless cycling, just waiting for the nitrites to drop before adding fish.

Criticism and advice are totally welcome.

I'm trying to post pictures as well. Hope they show up.

[David Hart]

 

The long sides 'will bow' with river rock. It doesn't take much to support them.  Mainland...$12 at the big home improvemnet stores.

[TCLynx]

I"m using some for my water chestnut/water cress beds.  They do bulge out on the sides and they are a bit shallow but they still work for many things.

[Ronald Holley]

Thanks David.

TC, I thought they looked a little shallow, how deep are they?

Don't we want at least 12" deep?

[TCLynx]

I think most of the larger mortar tubs are about 8" deep.  It is on the shallow side but 12 inches deep is simply a recommended depth and aquaponics can be done with deeper and shallower beds.  With the shallower beds you simply have less of that middle zone of media where the flood and drain happens so less effective bio-filter media.  It can still work.

 

Lets face it, many things work even though they are outside the "recommended" rules of thumb.  I've managed to root clog 24 inch deep grow beds by growing certain things in them.

[David Hart]

Great points ...TCL...

 

Ronald, I don't know if you saw my picture on page 2 of Larry's blog (this one)...?

 

That 'is' a picture of grow tub abuse...lol. I had sweet potatoes and okra growing in the 'same tub'. Not only that, the river rock is too small...only about 1/2 an inch.(Hey... It was 'free')

Thursday, I spent a good part of the day, pulling everything out...and rinsing the rocks. The tubs had become 'so full' of roots...for the last month or 2.... I'd removed the stand pipes from the bells. I had the water 'trickling' all the time into each bed. Any faster, and the water went over the side of the tubs.

 

The plants 'loved it ! '' I got a ton of okra off of the 7 plants.  My buddy grew up in FL. He had to help his granpa pick okra every summer....he said, he never saw so much okra on any one plant !

I didn't grow the seeet taters, for the 'taters'.....I grew them because 'they grow in the FL heat', and they use up some nutrients in the water. I ate lots of tater leaves....and the fish like the leaves too, better then duckweed. ( The sweet potatoes, were just starting to form 'potatoes')

One bed out of six, was 'just' statring to look like, it might of been becomming anaerobic. It was the one with 2 full grown okras and sweet potatoes in it...

 

I wouldn't recomending doing this. My system is somewhat of a hybrid...I do have a swirl filter (solids seperator) before the media 'tubs'. Plus I have a large bio barrel ( remember, TCL pointed out the 'tubs' have a very small 'bio' area.) My backyard system also has 300 sq ft of DWC beds.

Have fun...push the limits (carefully) and learn lots ...

[Larry]

Well put, if I had to wait for 12" deep grow beds I wouldn't have a system at all. The expense kept me at 8" GB's. But, I'd really like to talk about my siphon. Even with 8" GB's the GB's drain completely. This system does not use a bell siphon in a grow bed, it's an external siphon that is nearly 4" below the bottom of the GB's. The GB's empty all but residual water before they start to refill. Of course I'd like 12" GB's but I don't think the problem is as dire as one would think. OK, I am a rank novice and maybe I'm missing something, but getting the drain point to be far below the bottom of the grow bed seems to be significant.

Looking forward to your replies. I have so much to learn.

TCLynx said:

I think most of the larger mortar tubs are about 8" deep.  It is on the shallow side but 12 inches deep is simply a recommended depth and aquaponics can be done with deeper and shallower beds.  With the shallower beds you simply have less of that middle zone of media where the flood and drain happens so less effective bio-filter media.  It can still work.

 

Lets face it, many things work even though they are outside the "recommended" rules of thumb.  I've managed to root clog 24 inch deep grow beds by growing certain things in them.

[David Hart]

Wow, that is a great point Larry....

Sounds like almost all your media will be acting as a bio-zone. Also, most of your plant's roots will be exposed to more air. That's a big improvement over a typical bell setup, in a shallow bed....

[TCLynx]

Yes, the external lower bell for the shallow beds has that benefit.

 

And I'm glad you went ahead with what you can find since doing something is far better than sitting around waiting because no one is selling the "perfect" thing in your area.  What's the worst that could happen?  You already know what to watch out for and depending on what you grow, you might not have any of those problems.

[Tony Tarantino]

I'm a bit confused if the external siphon is 4 inches below the grow beds how do they fill with water before the siphon is activated

[TCLynx]

I think he means the bottom of the external siphon is below the bottom of the grow beds and the top is situated so that the grow beds flood to the appropriate level.  This way the siphon doesn't cut out until after the grow beds are drained all the way down.  Basically like saying the grow beds might only be 8" deep but the siphon is more like a siphon for 12 inch deep beds and the bottom 4 inches of the grow beds are virtual

[David Hart]

Tony, It might be more clear, if you look at Larry's 3rd picture....I agree with TC, the 'top' of the stand pipe,  'sets' the highest point of the water in the tubs.

 

Larry, I like your design enough, I may have to set up a few and give it a try...

[Harold Sukhbir]

Hi Larry,

I noticed the lower drain from your pics. I think the reason why constant flow shows faster growth than timed/F&D is because nutrient water and oxygen contact roots more so than in the case of F&D and ammonia conversion is also enhanced. I also believe the faster the cycling period in F&D the better. If the siphon can manage a faster fill/drain cycle then there could be real advantage this way. May be with the shorter bed height your cycles are as fast as other 12" beds?