Hi Guys, been making sketches and doing lots of plumbing in my head and it has created a couple of questions. First a quick explanation of my design. Thinking CHIFT-PIST design, FT will gravity feed to F & D beds, bell siphon into sump, pump back into FT. Here are the questions: How do I deal with solids? As the overflow from FT to beds will have to be near the top of FT, would it be a good idea to just have a valve at the bottom of the FT and drain a few seconds into a bucket every few (days) and just manually dump into beds?

The grow beds in a F & D design act as the biological filter, but when they dry out does the bacteria not die? Are they not really that dry for very long? I live in Tucson, 100+ degrees for 100 days in the summer.

GB volume vs FT volume, I have seen some discussion of this but nothing definitive, for a 150 gallon FT that means up to 450 gallon GB, is that total volume of GB (medium + water) or just water volume? Just water volume doesn't seem practical.

Are galvanized troughs OK for a GB or FT? I would think not, because it has Zinc in the coating. Is painting OK and with what paint?

Thanks for all the help!

Chris