Backyard Aquaponics
A place to discuss aquaponics

GROW BED DRAINAGE-
We have built an 700gal fish tank, pumping up to three 36feet x 30inch x 12inch media filled (mix hydroton and pea gravel) grow beds. One GB drains directectly into fish tank, the other two sump back to it.
Our problem is this- we slanted the grow beds too much. 1/4 per foot, meaning 8 inches over the 36 inch run. I am hoping to use bell siphons to flood and drain, however when the water reaches siphon height on the low end of the grow bed, the water is only 4 inches at the incoming end of the grow bed.
Possible solutions? We can't feasibly change our grow bed angle. We are considering cutting the grow beds in half lenghtwise, so they are only 18 feet long, and putting another siphon in there. That way cutting the water level problem in half, to a seemingly manageable 4 inches.
Ingenious ideas? Thanks a lot. Victor

Perhaps a photo of what you have got currently?

Some photos would be nice so we can get a better understanding.

Why isn't it feasible to change the angle?

Those are really long grow beds to flood and drain by a siphon. You may find that the end far from the siphon may tend to have water in it even when the siphon has drained it's end all the way down. Water doesn't move through gravel instantly, especially as roots grow. You may later decide that some form of timed flood and drain might be easier with such beds.

And since you slanted them so much, will be really tricky to even fully flood the high end without overflowing the low end. It is one thing to have the bottom of a grow bed slant but the top edge of things that flood and drain really needs to be as close to level as you can manage since water will find it's own level. Even if you cut them in half, you may find that the water is over the gravel in the siphon end and still well below the surface on the other end. If you can do something to level the top edge of the beds a bit, essentially leaving the one end at the same depth it is but making the siphon end deeper by raising the top edge? I'm assuming you used lumber/liner to do this, perhaps some trim along the top edge to hold up the liner a bit higher on the siphon ends.

Good Luck.

Cutting them in half would work, first I think I would try and put a dam in the middle of the growbed turning it into two growbeds with independent drains. Plug it up in two or even three places and you gain even more of the previously unused height. Since the beds would all be contained in the original bed, small leaks would not be an issue.

Just fill with water and level out the media to the level of the water, at the required hight. So what if the sides of the GB are a bit higher on one end at least it will be level.

You can put some air diffusers in the shallow end so that when the bubbles pop under the media, the moisture and humidity travel upward through and keep the rest of the media above it moist.