Backyard Aquaponics
A place to discuss aquaponics

I notice that nearly all growbeds are top fed and (of course) bottom drained

Is there anybody who has experience (good or bad) with bottom feeding of growbeds?

I have my solids filtered out in an upflow bead filter with solids settling, so that shouldn't be an issue

Frank

I think the only ones I've really heard of would be conversions of flood n drain hydroponic trays where the pump pushes water up through the bottom of the grow bed and then when the timer turns off the water drains back through the pump. I don't know how good or bad that would be depending on the type of pump but I suppose it would work for some limited small scale situations.

Yep, I have done it, only problem I had was hydroton coming back down the pipe when the pump was turned off Simple design problem, but otherwise it worked well, and there were no water clarity issues.

When the small system was changed to chift pist I reverted to the more standard type of plumbing.

Toying with making the next round of IBC's bottom fed...

nice to hear that my idea is not too stupid
and that others think along the same lines

I think it has some advantages: more planting surface
no pipes on the growbed

frank

Frank

Are you intending to flood via a second bottom hole or running the pipe over the top side and down to the bottom?

Since I only have one point of water entry (no grid here), I'm not loosing much planting area to plumbing.

that would be my intention indeed,
but I am in the designing/realization stage and my decisions might change by the hour as I proceed
will know more by the end of the week
so please give me feedback to avoid design mistakes

frank

My main worry about bottom feeding is the difficulty in seeing what is going on and fixing problems such as clogging. I do do grids feeding the top of my grow bed as I wouldn't want to have to clean them out regularly. If you were to do a grid in the bottom, it would be pretty difficult to clean out.
If no grid, how do you plan keeping gravel and roots out of the feed pipe?

It seems to me the root problem usually occurs with outflows not inflows. If you use a top to bottom pipe you would have to have a tee at the top to stop siphoning. You could always deroot it, if a problem, from the top.

My only concern Frank would be water flow restriction - okay if the inflow was under pump pressure but using venturi drain (or whatever it gets called) and gravity feed to the GBs, there is a real possibility of clogging due to GB media, plant roots or even sediment...take these into consideration in the design and bottom feeding would probably work well

As an addition, two of my gb's, in my scruffy system, bottom fill.
Fills the centre gb from the top and is fed to the other two by a bottom feed, balances then dumps on a loop siphon (ping pong balls stop air being bled into the siphon).
My only problem so far has been the amount of crap building up in the centre fill gb, reason is water comes from the pond which tends to get dirty easily.

Ya know, now that you mention your set up sleepe, I realize my Aquarium system kinda works that way. The end two buckets get fed at the top by the two aquarium but the 5 buckets are all connected together at the bottom and the loop siphon is only at one end. (makes me think I should really install an overflow before something goes wrong.)

Anyway, I'm using fairly large pipe to connect all five buckets together (1 1/2 inch or 40 mm) and I put parts of plant baskets over the point where the pipe enters the buckets to keep gravel from getting into the pipes.

Set up seems to be working ok other than the fact that I have less than 25 gallons of gravel for 50 gallons of aquarium.