Backyard Aquaponics
A place to discuss aquaponics

Do you AP "Old Timers" use non-return valves on your air lines or do you keep the pump above the water line? Do the valves effect the air pressure

I keep my pump and backbone (16mm pipe) above the water line - I noticed once after a power failure that water still got into the backbone where it dipped below the water level.

Not sure if a non-return valve makes any difference to air pressure or places more pressure on the air pump/diaphragms.

Always keep your pump above the waterline... if you can't (for some reason)... then definitely... non-return valves must be fitted...

i use the valves, even when the air pump is above the water line

I use them most of the time, we sell them with all our air pumps, but if I'm doing my own systems and the pump is up a fair bit above the water line I don't bother..

I've wondered about how much they might slow down the air flow because some of them take quite a bit of pressure to push through them. might run a test here to see.

Had to add them to mine. I found that on a power fail the water would siphon up 100mm or so to over the edge then fill my air line. Even tho the air pump was safe it didn't like trying to push that water out.

I only use them when the pumps below water level. Also remember... Check valves can fail too! If possible just mount above the water level. There are spring loaded check valves and flapper style. Both cause some back pressure but the spring type causes more. If you want an exact amount, look up the size of check valve on a friction loss for air chart. There are some good hard numbers for pressure losses on most sizes.

Ive used them on my 180ltr aquarium and have had them fail twice, so now I have the air pump screwed into the wall, well above the water line.

This thread led us to do a little experiment yesterday with our air pumps. We got two side by side brand new pumps, one with valves, one without, two air stones on each. Both sets of stones were dropped down to the bottom of our deepest tank, about 1m deep and the difference in air flow appeared to be the same, in fact, if anything the air seemed to be more through the one with valves which seems a little weird...

Not exactly what I expected, I thought there'd be a big difference between the two, perhaps we need to get the stones even deeper to tell a difference by eye.

Perhaps you could hold a clear container or bucket underwater with the outlet (minus airstones) inside, and time how long it takes for the air to fill it up...

Now you are thinking.......