Hang-On Overflow

[Secam]

Greg,

I learned a lot from your articles on sumps. I have an established 30 gallon reef. It currently does not have a sump, however I would like to add one. The stand that I have was not designed for a sump, but I do have easy access to my basement, directly below the tank.

The tank has not been pre-drilled so it appears that my only choice is to use a hang-on overflow. My concern is the same as your concern, namely, the chance that we could overflow the main tank should the siphon be lost.

Now I would have thought that someone would have invented a switch that either requires the presence or lack of presence of water. This switch could then be used to deactivate the return pump in the event of a clog or siphon loss.

I must assume that if there was a reliable switch you would have mentioned it in your article and it would be standard on each and every sump. Still, it begs the question.

One more thing. Do you know of any calculators that can help me figure out the return pump size while also taking into account vertical rise, which in my case would be about 10 feet? Is it good practice to oversize a pump and then use a valve to restrict flow or would this damage the pump?

Thanks

Jeff

 

[gregt]

There are switches that you can use to turn off the pump if the water rises too high and in fact I do recommend using them. There are two problems with that however. First, any switch can fail. Especially when it's in close proximity of saltwater. And second, if your pump is shut off then you do not have flow in your tank.

That said, niether of these are really that big a problem as long as you are aware of them. Don't be afraid to use a hang on overflow, just understand the possible problems with them and prepare yourself accordingly. And, whenever possible, drill your tank so you have that much less to worry about.

The calculator you are looking for is here: http://reefcentral.com/calc/hlc2.php

And I always buy too big a pump. You can alway throttle it down, but it's a tad more difficult to throttle it up. Most pressure rated pumps can be throttled back 75% or more without any damage at all. Some non-pressure rated pumps can have problems if you throttle them back. You shouldn't need to worry as you'll need a pressure rated pump to overcome the head pressures of your application anyway.

 

[Secam]

Thanks for your advice Greg, I appreciate it.

Jeff

 

[gregt]

No problem. Glad to be of help. Let me know how the project goes.

 

[RichTG]

Jeff, I designed my own overflow with pvc and to overcome the siphon loss problem, I simply ran flexible airline tubing from the venturi port on the nearest powerhead up into the overflow siphon to the highest point inside it. Every once in a while, that powerhead will shoot out a puff of bubbles, maintaining a constant siphon. It has been running for over a year and the only thing to consider is to find black tubing so algae wont build up and block the process. The powerhead also primes the overflow if your water level drops too low (water change, etc.) LOL, Rich.

 

[RichTG]

here's a crude pic to illustrate the concept better.