Reducing water velocity in return from sump

[Matt Ziemer]

I am currently planning the new plumbing in a tank upgrade. I have a pump that I tested at about 950 gph at a 5' head. The output of the pump is 3/4" threaded.

If I plumb a 3/4" line into my tank, the water is going to be blasting such that nothing will be left standing.

My idea is to reduce the velocity of the return water by adding a Tee fitting to split the return water into 2 inlets instead of just 1, and to step up the 3/4" line to about a 1-1/2" line to reduce the concentration, and thus the velocity of the water going into the tank. I will be plumbing a valve into the return line, of course, but I don't want reducing the volume to be the only way to reduce the velocity.

What do you guys think of this approach?

Any input is appreciated.

Matt Z.

 

[cdness]

If you want to reduce velocity, the T approach will work well. Add the t to go to two outlets. Place a locline fan diffuser to the end and you'll be all set. They spread out the flow to a wider output.

I wouldn't upscale the plumbing though...

 

[Genesis Corals]

How big is the tank, because 950 gph is probably not as much as you think it is. You can also put a ball valve on the return to restrict the flow, just don't use them on your drains.

 

[AZDesertRat]

Both methods mentioned will work and I would and actually used both myself. One thing worth mentioning though is increasing the line size on the return will give you lower headloss due to friction so will raise the pumps GPH slightly. If you want to reduce the velocity I would stick with the 3/4" up to a tee then branch out in each direction with 3/4" and exit the returns via short sections of 3/4" LocLine and fan nozzles as already mentioned. Right off the pump I would install a short section of 3/4" reinforced vinyl tubing to reduce vibrations and sound transmission and to allow some movement for misalignments and plumbing stress then install a 3/4" ball or gate valve to throttle flows to suit your needs.

This will also allow you to fine tune your overflow rate in the internal or HOB overflow box to make it quiet and efficient since it is the pump that determines your overflow rate, not the overflow box if sized properly.

You could also branch each return into LocLine wyes and have two outlets from each return as long as you make sure they do not extend too far down into the water causing floding in your sump during a power outage. I had my return with dual LocLines on each at one time but went back to two single returns and added a Oceans Motions Squirt two way switching device and controllable powerheads for more random flows.

 

[Matt Ziemer]

The tank is 135 g. I bought the pump based on a manufacturer spec of 1500/1300 gph at 4' and 6' heads respectively. My system will have a 5' head, so I figured I would get about 1400 gph - so basically 10x volume exchange hourly. When I got the pump, I plumbed it with a 5' head, and drained 20 gallons out of my water mixing container in 1:17, which I calculated at about 950 gph.

I was very disappointed at the magnitude of variance between the actual performance and the manufacturers stated specs. But at the same time, the velocity of water coming out of the 3/4" line was very concerning to me. I think I'll be ok with this volume turnover, because mine is an LPS dominated system, so I should be able to get by without the massive exchange I've seen SPS guys recommend.

Also, the fact is, my current exchange rate is really anemic, but my reef is doing just fine. Always trying to set it up tho.

By the way, I do have valves on my single drain right now, but it's only for setting up the siphon. My tank is not drilled, so I am using a DIY overflow like to type pictured below.

 

[Matt Ziemer]

AZDesert Rat, thanks for the ideas. I had no idea about the Oceans Motions products. I just looked into them, and I really like the idea. I currently use "wavemaker" power strip, and power heads to create alternating flows in my tank, but with an OM product, I can incorporate my new increased flow from the return pump. It's gonna have to be a "wish list" item for now, tho.

I am definitely going to install a section of flex line. I am currently running flex all the way to the top of the tank, and then transitioning to a pvc fitting just to hook over the lip of the tank. I planned on going with all hard line in the new tank, but it's a great idea to have one spot of "play."

As far as having the return nozzles shallow in the water to prevent flooding my sump during a power outage, I currently have the return nozzle submerged, but very shallow for this very reason. I currently do not have a check valve in place, but my new system will have a check valve. Isn't this an adequate insurance against this particular issue? I plan on not worrying about how deep the return nozzles are in the tank, but if there's a history of check valve failures in this application, I would be interested to know that.

Anyway, thanks again.