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Comment by Brent Zionic on October 11, 2010 at 5:44pm

Great link - thanks for the assistance

Comment by TCLynx on October 11, 2010 at 4:45pm

Here is a link to a blog post where I go over a lot of the basic design numbers I use when designing my systems.
Design Blog

Comment by TCLynx on October 11, 2010 at 4:40pm

I would say turn your tank volume over at least once per hour.

Comment by Brent Zionic on October 11, 2010 at 4:10pm

Fantastic idea, thanks for the tip!

Are there any rough guidelines out there for how quickly the flood and drain cycle ought to work? I'm thinking like a table for size of the tank based on the ratio of tank to grow bed (I understand you can go roughly from 1:1 to 1:2 for flood and drain, and maybe up to 1:3 for raft systems?)?

I scribbled in my notebook the following somewhat cryptic comment: "Turn your tank water over every few hours, 3-4 times in a cycle." I wrote that down listening to JD Sawyer at the Growhaus, but I can't really make sense of it now (through no fault of JD's).

Comment by TCLynx on October 11, 2010 at 3:43pm

To slow down the rate at which the grow bed floods, you can add a bypass off the pump to spray back into the fish tank. Use a T and a valve on the feed from the pump up to the grow bed and return the water from the valve back to the fish tank with a spray bar or something and you can adjust the flow with the valve to a rate at which the bed floods and drains properly.

Comment by Brent Zionic on October 11, 2010 at 2:54pm

This is my first attempt at building a mini-system.

I decided to go with a small 10 gallon aquarium and a 10 gallon grow bed with hydroton and a bell siphon. Total cost of all parts came to < $200 (USD), with the most expensive part being the $40 water testing kit.

I placed it on a nice rolling cart rack so I can wheel it out onto my deck or roll it into the shower in case I want to. Not sure why I would, but I can!

Originally I had a straight down drain tube but it was spitting a lot and spraying. I had it about 5 inches above the top of the aquarium, so I added a T joint and about a foot of horizontal 1 inch PVC drilled with drain holes, and this works much better. However, even with my adjustable water pump on minimum, it can full the grow bed to the drain pipe top in about 2 minutes 34 seconds, and then drain in 24 seconds.

The drain action is quite fast, and I fear I made it too powerful and should get a little slower pump, or perhaps some things in the tank which my fish can hide underneath. I picture them all having little heart attacks every time the siphon kicks in and floods them.

I thought I'd share this for any other first-timers who are thinking about taking the plunge.