sump pump placement

[DocOops]

I posted the following in the main reef board, then found your author section in one of your plumbing articles:

I will be setting up a 180g reef soon and will be locating my chiller outside - plumbed through the wall. I estimate using approximately 20 ft. of 1" (or 1.5"?) PVC and 4 90 degree turns (total to and from the tank/sump). Can I locate the main pump (a GRI 520) outside with the chiller to minimize noise? The tank's going in the family room and my wife wants it to be as quiet as possible.
There would then be a horizontal/slightly downhill run of 10 feet from the drain bulkhead in the sump to the pump outside; my LFS said that would be OK but I seem to remember seeing posts here suggesting that the pump intake should be as close to the drain bulkhead as possible. Why?...the chiller (and pump if possible) would be about 6" lower than the sump so priming shouldn't be an issue. Is cavitation the problem or is there some other issue I need to know about?
(I know this is a lot of flow through the sump; the GRI 520 is rated approximately 1500 gph at 6 ft. head and is pressure-rated. I'm planning an Ecosystem-type refugium/sump, and they recommend 1200 - 1500 gph)

Thanks for any input.

 

[rexn]

I do not think you should have too much trouble with your planned set up.

Cavitation is normally caused by have too large an equivalent head or restriction on the input of the pump and if the pump is lower than the sump as described then you should have little to worry about. If you plan on having a valve for flow adjustment purposes make sure it is on the outlet side of pump to also minimize possible cavitation issues.

As for locating the pump near the sump, as long as the issues of priming and possible cavitation are addressed I do not think you should have a problem. I would suggest you install valves on both the inlet and outlet sides of the pump along with some unions to make for a quick disconnect arrangement for easy maintanance on the pump and chiller. You will probably want to locate these [valves] near the external pump to minimize disturbing the plumbing once its in place.

If it is possible I would probably go with the 1.5" plumbing as 20' run is sufficiently long coupled with your desire to operate near the upper end of the pumps rating to try to minimize losses from the plumbing itself. Your 4 90 elbows will probably be the largest flow loss contributers so if there is some way to replace some of these with a more gradual bend using tubing or the like you might wish to consider this.

Last observation is not related to the plumbing but with respect to locating the pump and most importantly the chiller outside as your planning. I do not know if they will be in shade, covered or in the open. If the latter or if your climate gets hot make sure the ambient air temperature around these units does not get above 90F as their reliability may be seriously compromized. The most successful outside installations of chillers I know of are under houses in the crawl spaces where the year round temperature is better controlled. This may not be practical for you nor needed but just a word to the wise. If you plan to enclose the units make sure they are adequately ventilated as their self heating could easily raise the surrounding temperature to undesirable levels.

Good luck, RN

 

[DocOops]

thanks for the reply - my wife will certainly be happy to know that the noisy components can go outside. I'll try to use sweeps or flex PVC instead of the elbows, as well as 1.5" pipe for the entire circuit. As for heat - it occasionally gets over 90 degrees in the summer, and I guess I'll have to put up with that. My only alternative is housing the chiller in the stand, which would both be noisy and inefficient.
thanks again - your advice is appreciated