Backyard Aquaponics
A place to discuss aquaponics

I got my cap end for the tank done.

Looks a little rough, but it should do the job. I can raise and lower it with a few washers on the bolts (both are stainless steel).

Sorry Colum, into the elimination round for that presentation.

(BTW I hope it works ok)

Colum that is going to be a pain to clean. Can you raise the 90mm up to the water height and put a 100mm pipe on he outside of that with holes on the bottom. This way you lift the 100mm pipe out clean it and put it back without loosing fish down the drain.

I'm not 100% sure what you mean.

In my RFF, there is the 90mm pipe that is at the water height, so that makes sure the height of the tank stays level. I left the 100mm cap unglued, and was going to put a hook, and then I can pull it off with something. Then I can put the 90mm pipe through the middle of the 100mm cap and block off the tank if need be.

Or am I missing something else?

Ummm, is the cap skirt bolted to the floor or resting on the floor?

If bolted I agree it will be a pain.

I'll throw my 2 cents in...
Take the cap off, put a coupler on that stub and then another section of pipe into the coupler and bring it above the water level in the tank but below the tank lip. Put a screen around it and this will act as an emergency overflow. If you come out and water is flowing through the center overflow, you know there is a dead fish or something clogging the skirt. Keep a small broom handy to knock anything loose.

Does this help.



With this you possible would not need to remove the outer pipe for cleaning as a simple twisting action may clean it. The size of pipes should be to suite your fittings in the base of the tank as the 90 and 100 are just nominal for the drawing.

Jonny5 is talking about a bottom draw standpipe which is similar but if you have a wide skirt on the bottom drain it doesn't work.

That design can significantly add to the friction losses. Depending on the rate of flow (velocity) the friction between the inner and outer walls can be significant/large. If trying to make a system as energy efficient as possible not a good idea.

If you already have the level set by an external standpipe you don't need an internal one as well. There fore if you cut two notches from the center pipe near its base the water will not go up and down but rather through the inlet slot (gap between skirt rim and tank floor) and straight into the drain.

That way the center pipe above the notches is just to hold the outer pipe and skirt in place. Same idea as the eyebolt really except there is a handle above the water to allow you to lift the skirt to clean it. Works just as well for tanks where you can reach the center (either from the side or a walkway above). Where you can not you well need the eye bolt and a pole or equivalent.

For large tanks it is cost effective to have two center drains. One small one for regular use and a larger one for flushing the small one and picking up dead fish. Cornell used a design that was hydraulically operated so when you saw a dead fish you pulled a lever and opened the large drain to flush it out.

Sorry Colum I missed that you might be using an external stand pipe. This should be more like Ryan was explaining.

The extension of the drain doesn't have water flowing through it but is there to keep the cap/outer pipe in place.

If it wobbled around too much you could put some space in around the center pipe.

That should be pretty easy to make work. Makes it easier to fine tune the height the skirt needs to be, although, I see myself getting wet with it. Pretty easy not to bolt it down as well, I was just paranoid about it getting knocked off, I might make a twist into place thing for it.

Any suggestions on what to use at a fine screen to stop the fishies jumping down the center bit of the pipe?

Thanks for the help!

Fine gutter guard, I had some on the bottom of my SLO and worked well while in place.

Can you explain the standpipe design a little more please Stu. Is this the way AQ tanks are plumbed? I get the inner standpipe sets the water level (within reason) but I'm not quite getting the purpose of the smaller pipe between that and the drain.