Increased pipe size on return pumps

[anothermineral]

I have a Hammerhead pump (1.5" in / out) and I'm interested in increasing the output piping in order to improve head loss.

When I use the head loss calculator, it shows a substantial improvement going from 1.5" to 2", however, when you increase to 2.5" or 3", the gain is marginal. I infer from this that there is a point of diminishing returns. What I'm not sure of is if there are any negatives to increasing the output pipe that are not obvious?

Any thoughts would be appreciated.

 

[fat-tony]

ok, i "think" this is how it works.

You have a small diameter tube you're pushing water through. When you're forcing that water through, the water is of course casuing friction in the pipe, but also against the water itelf taht is touching the pipe. As you get bigger, you have more water getting pushed by in the middle without touching the sides and adding to the friction.

After you keep going up in size, you hit a point where it kinda works like a fountain. You have the water in the middle, but because of the lack of tubing near the middle, it almost falls on itself on the outside.

I'm not sure if that makes sense how i explained it, it's easier to visualize if you've ever seen the different sizes work.


If this is as a return, you need to take things like overflow capacity into consideration, otherwise you may be throttling back the pump after you upgrade and negating the work done.

 

[flyyyguy]

No negatives from increasing your output piping and there is most defintely a break point in which going bigger ceases to improve much.........however,

There is no value to moving any more water through your sump than your skimmer can process. If you do, you are intentionally setting it up so that your return pump will send massive amounts of unskimmed water back to the tank and skimming less efficiently than you could be.

While skimming 100% of the water that goes through your sump is unrealistic, roughly matching skimming capacity to return flow will at least be making the effort.

I know of very few people who need a hammerhead for a return pumpmost reefers fall into the 300-800 gph category. Remember your return pump may be rated at 500 gph or 1200 gph...whatever, but you are pumping air alogn with that water and not processing nearly what the pump is rated for in gph

 

[anothermineral]

fat-tony, thanks for the explanation, that's how I thought of it as well, but was looking for confirmation.

flyyyguy, I agree it would be best to skim as much flow through the sump as possible, however, in my case, the HH will be returning to multiple tanks. The value to me is having one pump support high flow volume (b/t 2400-3000 gph). Since I cannot affort the skimmer required to skim that volume (who can?), it's a trade-off I'm willing to make.