Backyard Aquaponics
A place to discuss aquaponics

Considering the bottom 4" never drains completely, and I'm down a couple of inches from the top with substrate, I would say it would flood in about 8-9 minutes. Is that timer fixed at 15 on 15 off? When I had a green house I had a timer I could dial in duration and frequency for misting. I don't remember exactly what it cost but I remember it being pricey.
I have a lot of great ideas to consider, thank you all very much.

Naw, it is one of those mechanical timers that has the little switches on it. Each switch represents 15 minutes so you could have the pump run for 15 minutes and then be off for 45 minutes or whatever seems appropriate (it is how I'm running my "quarantine system" currently.

I think I picked up a couple of those timers from Skycraft for about $13 each but I've since seen them at Lowes or Home Depot for probably the same price as on Amazon. That timer can easily handle my 300 watt (1/6th HP) pump in the quarantine system but probably not be appropriate for a big pool pump.

It is really easy to find 1/2 hour increment outdoor mechanical timers but the 15 minute ones with the switches for outdoors are not as common.

right, I would definitely need an overflow in that case as 15 minutes would assuredly be too long, but not by much.

a few more pics....

Overflow set to and inch below the surface of the gravel is a good idea in any case.

Now if it takes say 8 minutes to flood the bed with the valve at the bottom closed. Then if you open the valve just a bit you might be able to adjust the drain rate such that it will take the full 15 minutes to fill the bed. However, I still think the overflow will be a good idea.

To keep algae from growing in that clear tubing, I recommend wrapping it in tin foil or something unless simply replacing it would be easier.

I've got plenty of gaff tape. I imagine the sun would effectively melt it to the hose over time.

Gaff tape would work, just don't ever plan on removing it from the hose. Though it might come apart of it's own in time. What ever you can do to keep light off the tubing would be good. I just recommend the foil as it's easy to pull off if you want to peak at the water flow on occasion.

Ian you are so right about the grid holes getting blocked with gunk. I checked today and at least 5 holes were completely backed up with gunk. I'm going to build a new grid this weekend based off your diagram instead of mod-ing the existing one so I have a fall back in case I screw up. I don't have a router but I have a nice thick Dremell bit that I think will get the job done (if I can follow a straight line).

Don't stress too much about making it pretty, the water won't mind too much

Just be careful not to slip and cut any holes in yourself.

I would like to see how this grow tub does if left as is, interesting ideas that are worth testing... but add another Rubbermaid doing flood & drain of some kind.
The 4" minimum water doesn't bother me, consider that's a little over what a FLOUT leaves at the bottom too.

Troy, can you get the larger (300 gallon) Rubbermaid tank too?

Rick

yeah they do have them, they don't list the dimensions and from the picture it looks like they would be to wide for my cool deck. Only $209 at Tractor Supply Company. I do plan on building at least 3 more tubs, the exact design is up in the air.