A new 150 gal greenhouse ebb and flow in Los Angeles

[Roe Sie]

Hello Everyone,

I just finished setting up my new system here in Los Angeles.

150 Gallon FT

<150 gal grow bed volume with hydroton media

Ebb and Flow

30 Hybrid Tilapia (I think that's how many are left...)

PH 6.9

Temp 82.5 degrees

Solar powered bubbler

Trying to grow duckweed, any advice on that  is welcome. If there is anyone in the Los Angeles area, would love to get in touch. I found a super cheap source for stock tanks, wondering where to buy a 400W tank heater before next winter.

Anybody find a good source for tilapia in the area?

Roe.

[RupertofOZ]

I think you'd obtain better results... and better control of water quality for your fish....

If you were to convert to a standard top irrigated flood & drain... rather than ebb & flow....

[Roe Sie]

thanks for the tip, i'm new to this so I'm learning as I go. Seems like a pretty simple change to make. is that to get better circulation of water in the bottom of the grow bed? or is it to get the top of the grow media wet? 

[RupertofOZ]

Ebb & flow pushes the water, containing solids up into the media... more particularly the bottom of the media...

 

Then pulls solids back down again.. through the pump and back into the fish tank....

 

Continually compacting solids into the bottom of the media also limits the oxygen exchange of the water going to the fish tank...

[Fred]

Hi Roe,

Looks like a nice setup for a greenhouse.  I'm in the LA area but opted against a green house as I was worried about the high temperatures during the summer.  I setup a drain and floor after looking at different options.  I think the Ebb and Flow might lead to more accumulation of solids so i went with floor and drain.  I also wanted to avoid a timer and just run a constant pump.

I'm looking for tilapia as well but the only found a source off craigslist.

[Roe Sie]

Hi Fred!  

Yes, temps get high, however, I bought automatic greenhouse vent openers and they work amazingly well! they are little brackets with heat sensitive hydraulic pistons that open the greenhouse whenever the temp goes above 90. They're a little pricey, but at $70 each, it's worth saving the plants (one day before I got them I forgot to go down and open the vents and the plants almost kicked it) We've had a couple of hot days since then with the new openers and the plants did fine. One benefit of the greenhouse is that it takes a lot less energy to get the fish tank water up to 82 degrees.

Are you still looking for tilapia? the guy I found off craigslist was down near santa monica and he sold me 25 hybrid males for $2 each (and he ended up giving me 35). he had a pretty sweet system set up. I if you want I can track down his email and send it to you. 

Fred said:

Hi Roe,

Looks like a nice setup for a greenhouse.  I'm in the LA area but opted against a green house as I was worried about the high temperatures during the summer.  I setup a drain and floor after looking at different options.  I think the Ebb and Flow might lead to more accumulation of solids so i went with floor and drain.  I also wanted to avoid a timer and just run a constant pump.

I'm looking for tilapia as well but the only found a source off craigslist.

[Roe Sie]

Hi Rupert. As you suggested, I added a top irrigation pipe, with holes drilled all the way down so I got a nice shower covering the whole grow bed. However, i seem to have inadvertently created a new problem: I noticed when the pump turned off, the grow bed stayed full! It didn't occur to me there's no way for the water to drain back in to fish tank. How did you solve that problem?

Previously, the holes in the riser coming up through the bottom of the grow bed tank were right at the base, so when the pump turned off the water ran right back out the same pipe. Now, the holes are over the grow bed so the tank just stays full. I'm sure I'll figure something out...

RupertofOZ said:

Ebb & flow pushes the water, containing solids up into the media... more particularly the bottom of the media...

 

Then pulls solids back down again.. through the pump and back into the fish tank....

 

Continually compacting solids into the bottom of the media also limits the oxygen exchange of the water going to the fish tank...

[RupertofOZ]

Well Roe.... you've got the flood part of flood & drain... down pat... now you just need the "drain"...

Two ways.... depending on whether you pump continuously... and use a bell siphon... or use a timed F&D.... with an overflow standpipe...

Both utilise a standpipe... plumbed through the bottom... to set the flood height.... (you'll need a ball valve to adjust the inflow either way)...

 

A siphon system has a "bell" over the standpipe, and is pumped continously.... the rising water forces the air up into the bell, until it displaces the air down through the standpipe... initiating a fast drain siphon...

 

The timed system just utilises an overflow stnadpipe... where the water rises to the top of the standpipe... which sets the height of the flood...and then overflows down the standpipe back to the tank...

(Just plumb the standpipe drain through the hole you were using to pump the ebb & flow...)

 

When the timer/pump ceases... the bed is slow drained by a couple of small holes drilled through the base of the standpipe...

 

I've got pictures if you want to email me... but I think TCL has some diagrams posted somewhere...

[Roe Sie]

Rupert,

I have a pipe running across the top with holes all along to sprinkle the top of the grow media. I've noticed the stems of my veggies don't seem to like that, and the hydroton is turning green. should I just have the water dropping in at the end of the pipe, or is this normal?

[TCLynx]

Here is one place with

Useful Diagrams

The distrobution irrigation grid should have the holes pointing down into the media so that most of the top of the media stays dry.

The drain pipe should have a stand pipe to set the max flood height and some small holes near the bottom to allow the bed to drain when the timer turns off.