Will this work? Overflow Mod (added underflow)

[peds82]

I am starting a new 180gal tank with a sump tank connected to a FBF for filtration. I need help figuring out the plumbing before i actually saw and glue my PVC fittings. I had my tank drilled on the upper left part of the left side. I modified the overflow in such a way that it will also have an underflow pipe to suck debris and dirt from the bottom of the tank. Here is a rough drawing of what i plan to do.

Will this work? During a power blackout, will the water line drop to the red line? Or will it completely drain the tank until the end of the underflow pipe?


+/- Inputs will be greatly appreciated. Thanks guys.

 

[frasertheking]

add a hole or a syphon break in the underflow pipe just at your lowest safe water level . then it should be fine

 

[peds82]

add a hole or a syphon break in the underflow pipe just at your lowest safe water level . then it should be fine

hey bro, thanks for the quick reply. i'll just drill a hole like what u suggested.

just another question though.. what if i make the design simpler by doing this instead?

will it still work?

 

[frasertheking]

i do not see a problem but i would wait for some of the more exp guys to come in . just to be sure

 

[ar0wan]

I think adding the 'underflow' will drain the tank to this lvl. The only way this would not happen is if you used a larger pump than your drain pipe can handle (not advised).

 

[CHOMPERS]

The top of the tee is a... ...hole. Any more holes would be pointless.

One if my tanks is plumbed like the last pic...without the extra hole.


To maximize the amount of water that the system can flow, add an additional tee to the outside opposite to the existing tee and then add a short piece of pipe to the top edge of the tank (to prevent flooding). This will allow the bulkhead fitting to flow 100% water instead of also partially drawing air.

 

[peds82]

The top of the tee is a... ...hole. Any more holes would be pointless.

One if my tanks is plumbed like the last pic...without the extra hole.


To maximize the amount of water that the system can flow, add an additional tee to the outside opposite to the existing tee and then add a short piece of pipe to the top edge of the tank (to prevent flooding). This will allow the bulkhead fitting to flow 100% water instead of also partially drawing air.

Thanks for the response chompers! I've been secretly wishing that you answer my post. I've gone through the whole thread of making your own DIY overflow using PVC pipes and i believe that you will give me sound advice.

Have you had any problems with your tank that is plumbed like the second pic? Does the hole on top of the tee break the siphon in case of a power outage? I don't quite get your idea of adding another tee to the outside opposite to the existing tee...can you illustrate this for me? Thanks man! i owe you one!

 

[CHOMPERS]

The second tee will be a mirror image of the one you already have. It will be on the other side of the bulkhead outside of the tank. It is to vent the plumbing going to the sump. If that side isn't vented, the plumbing will just vent itself through the bulkhead. Unfortunately if this is the case (as in mine) the air that is drawn in through the bulkhead must replace water volume. If the plumbing is externally vented with the extra tee, then the bulkhead can flow 100% water if it needs too.

 

[peds82]

The second tee will be a mirror image of the one you already have. It will be on the other side of the bulkhead outside of the tank. It is to vent the plumbing going to the sump. If that side isn't vented, the plumbing will just vent itself through the bulkhead. Unfortunately if this is the case (as in mine) the air that is drawn in through the bulkhead must replace water volume. If the plumbing is externally vented with the extra tee, then the bulkhead can flow 100% water if it needs too.

I get it now bro thanks! that's a really clever design! i'll post my tank here when its done. Thanks for all the help guys!

 

[Bawb2u]

Like Chomper said, that system, especially with the other tee will work fine. The only problem I can see is it'll be fairly loud as the water rushing down the pipes will draw in air also. I don't think it'll draw as much off the bottom as you think if you leave the entire tee open though. Water takes the path of least resistance, so more will be skimmed than sucked up a distance. You could put a cap on the top of the tee inside the tank with a hole in it, maybe about a half inch, causing more water to come up the tube but still allowing enough water to go into the tee to start a flow.