DIY Overflow

DIY Overflow

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This overflow is installed on my wife's 75 gal turtle tank which used a GenX-2400 (around 500 gph) as a return pump. A DIY overflow was necessary since drilling the tank is out of the question and this tank is only kept approx 2/3 full of water.

The interior and exterior 'overflow chambers' are 4" ABS plastic pipe. The 2 siphon tubes are 1" PVC running from the 'inner overflow chamber', up and over the tank wall and are plumbed through the exterior of the 'outer overflow chamber' near the bottom (see pic # 2). This was done by drilling holes on both sides and threading the ABS to accept 90˚ street ells.

On The top of the siphon tubes I have drilled and installed an air hose for quick priming (see pic 5-6). These pics show the hoses hanging inside the 'inner overflow chamber' but now I just have them hanging over the back of the tank down to the sump with 'pinch clamps' to pinch the hoses shut.

On the bottom of the outer overflow chamber is where the siphoned water exits to the sump. I installed a DIY Bulkhead Fitting then the Durso Standpipe shown in pic #5 was installed to make the overflows operation as silent as possible. A standard 1" Durso Standpipe will not fit inside of the 4" outer overflow chamber so it had to be cut down and glued in order for it to fit (shown below):

Durso Standpipe

Also See 'Overflow Standpipe Page'

NOTE:

After a while I upgraded the return pump with a Little Giant 2-MDQX-SC. The upgrade significantly improved the flow rate therefore the overflow needed to be modified. A 1" bulkhead fitting can only allow around 600 gph flow rate.

Head (ft)	Flow (GPH)	Head (m)	Flow (LPH)
1	770	0.3	2914.8
3	640	0.9	2422.7
6	370	1.8	1400.6

1	I first replaced the 1" DIY Bulkhead Fitting with a 1-1/4 bulkhead fitting
2	I then replaced the 1" Durso Standpipe with a 1-1/2" Standpipe and used a 1-1/2" to 1-1/4" female adapter. The Durso NEEDED to be replaced with a Stockman Aquasilencer because a Durso of the appropriate size CAN NOT fit into the 4" ABS

Stockman Aqua-Silencer

Improvements/Modifications:

Instead of drilling holes in the top of the 'inner overflow chamber' to allow water to enter, I would prefer teeth or much larger holes.
I would install a Union either before or after both Street Ells (see pic # 2) for quick disassembly and easy cleaning. Siphon tubes can eventually build up algae growth.
Regardless of the size of the overflow or the gph rate of the return pump, I would suggest using the Stockman Aqua-Silencer. A much larger standpipe can be used if necessary because it is round.

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