As everything cheaply put together this design is coyote ugly. But you can put it together for about $5 and fast!
The design is nothing new but I don't think everybody knows about it. I post this thread in the "Filtration" section of the APC forum because probably, as more people understand the importance of a big and well oxygenated biofilter, the use of sumps in the aquatic plant hobby will increase. And overflows will get more interest.
So. The DIY overflow video is from Joey, a guy that apparently makes money off the YouTube ads. His tutorials on DIY are put together with a very basic understanding of what he is doing. There a bunch of details that I don't think he even knows about that will make the wonderful DIY project go bad (at times very bad). Keep that in mind when you watch the DIY overflow video too - there are a few details that will not just make the overflow work pretty bad but can drain all the water from your tank one sunny day (or rather night, because things like that never happen during the day as we all know).
The video is good because Joey shows an animation of how the DIY overflow works. I wish his comments were not being read from a quickly scribbled sheet of paper but please know that finding a good video that explains this kind of DIY overflow is not easy. http://www.youtube.com/watch?v=7DFk4bnIxEg Good things about the DIY overflow:
1. Cheap - $5 for even a high flow rate design
2. Put together in 10 minutes
3. The intake pipe can be rotated in any directon - does not have to stick forward. Can be turned to stick to the back glass. Things to consider:
1. The check valve used to prime the overflow is usualy glued to the PVC in a very flimsy way.
People assume that the strong PVC glue used to glue PVC pipes together is a miracle. But it does NOT work on all kinds of plastic. Check valves are not PVC. The glue does not work very well for them. What to use to glue PVC pipe with some kind of unknown plastic - it's your guess. Screwing the check valve is the best design but "cheap" normally wants things "fast" too...
The check valve can pop out at some point and water will start to drip on the floor. Maybe the small hole will introduce air into the overflow and the syphon will stop. This is bad, very bad, read on why. And if the syphon does not stop that's bad too - there will be at least some water on the floor - until the water level in the tank gets lower than the intake end. The sump pump will continue moving water no matter if the overflow works or not. If your sump is a nice big size the tank will overflow over the glass edges until the sump is empty. Now in addition to wet floors the pump will start to run dry, eventually overheat, probably melt, and maybe have an electric short sitting in 1/2" of water. Be VERY careful walking on that wet carpet - it may be electrified. Fun, eh... As you see - a tiny detail (a check valve hole) can cause a huge problem.
2. The intake pipe must have some kind of filtering cap. Snails, algae, debries, live fish can get in the pipe if it is open ended. Protecting the opening means you have to maintain it clean on a regular basis.
3. Drain pipe must be kept open at all times. Or the standpipe will overflow. Or the tank will overfill.
4. It is not easy to find black or grey fittings. Gray PVC pipe is easy to find. So you will most likely end up with bright white fittings. Ugly. Yes, you can spray paint them black with Crylon paint from Home Depot. DIY never rests in its effort to save a few bucks
5. Overflow can be noisy. From the water going through the pipes. Sucking noise 24/7 in your living room - welcome to the world of sumps. And yes, there are ways to mitigate that problem but not guaranteed to work every single time. This problem is akin to screeching water pipes in your house - hard to pinpoint and fix.
I posted a link to the "Filtration" section of APC as a comment in one of Joey's videos about making a big, large, huge PVC canister filter out of a PVC pipe. It is a design impressive to every individual with zero knowledge of how biofiltration works. The recently translated from Dutch information about biofiltration would have been important to know when building a monster size filter. I guess Joey realy doesn't like competition with external links because he banned me from posting comments on his DIY videos altogether. 50K+ views on each one of your videos can make you grow a bit of a big head you know