Return Plumbing - to upsize or not

[MergeConflict]

Hey yall;

I currently have a 150g display with a ~40 gallon sump, SICCE 5, Artica cooler and manifold. All return plumbing is vinyl 3/4" i.d. and is laid out like so:
return -> cooler -> manifold (which is closed most of the time unless i need to run carbon) -> tank. The cooler was added after the original install/specs for the system.

After installing my cooler I noticed that the flow through the return has diminished a quite a bit and it has caused me to hold off on installing a UV filter into the system until I upgraded pumps.

Well; I just got in a COR 20 (because might as well do all the Neptune things), but after some reading I'm learning that the flowrate through about 10' (length, height difference is less than 5') of head is only about 1200gph, and there is some additional loss due to reducing the plumbing i.d. from 1 1/2" to 3/4".

As "luck" would have it I got a case of ich, and have caught all the survivors, so the tank is sitting fallow and seems the time would be right for any drastic plumbing improvements.

So here's my question, due to all the accessories (cooler, UV, manifold) should I just go ahead and upgrade all the plumbing to 1 1/2"; and if so should I then move the cooler to the manifold since it only allows for 3/4" in/outlets? I'm trying to achieve 4-5x through the sump. I have been toying around with just using the SICCE 5 as the feed for the cooler (or cooler and UV) and feeding back into the sump.

Thoughts/suggestions?

 

[Reefer Reboot]

Yes, yes and yes! The id of schedule 40 3/4" pvc pipe is .804" (a cross section area of .507 square inches), id of 1 1/2" is 1.59" (a cross section area of 1.985 square inches) That's almost 4 times as much area for the water to flow through greatly reducing the resistance to flow.

 

[DCR]

Chillers and UV's add a lot of head loss. I would not put it on your main return to the tank or you will reduce the return flow as you have already noted. I would come off the manifold and return to the sump for those items. I would upsize the manifold to 1-1/2" and have at least a 1" return to the tank which should give you at least 600 gph.

 

[Saltees]

Can’t say how you should run yours, but to share how I ran mine.

I had my COR20 returning water from sump to display with a UV in between. I was getting 1,600LPH (3x my total water volume) with COR20@50%.

But when I put a chiller + 3m of flexible hose after the UV, the flow dropped to 800LPH with COR20@100%.

COR20@Sump > UV > Chiller (1/2” I/O) > 1” Flow Meter > Display tank.

1” flexible hose was used throughout the install. And my RSR500P comes with an 3/4” stock return.

I’m not complaining at the flow reduction as I have plenty of flow via 2 WAV in tank. And the 1.5X through sump flow provided plenty of dwelling time for my skimmer and ATS. If ever for whatsoever reason I need more flow, I will run another COR20 in parallel on the same line, granted it will be less efficient, but for sure the flow will be more.

I hope the above helps.

 

[schuby]

I have a chiller and the internal tubing is either 1/2" or 3/4". With your chiller still inline, you won't get the full benefit of the larger return plumbing. Despite that, I wish I would've used 1" return plumbing myself instead of 3/4".

My vote is that you take this unexpected opportunity to re-do your return plumbing for the best current and future benefits.

 

[Sablah]

Using a separate pump for the manifold and chiller is probably a good idea. I don't know much about chillers, but I would guess its fine to dump the output back into the sump. However, you do not want the UV to dump back into the sump, you either want to plumb it into your return or have it in a closed loop. (BRS did a few videos regarding proper plumbing and flow for UVs 1, 2, 3). There's also two different minimum flow rates for UVs (one for algae and one for larger things like ich), so make sure to meet the minimums of your specific UV. Your chiller has a min/max flow rate as well, so make sure to take that into account too.

Increasing the diameter will reduce the total head, but as to how much it will help you would need to compare in a calculator like this one. If the return plumbing is sch40 PVC, 10' horizontal, 5' vertical, and 3 elbows, and targeting 750gph, then you'd be looking at a head loss of ~10.1'. Plumbed in 1.5", the head loss would only be ~7.8'. Add on additional plumbing, the manifold, equipment, etc, you won't be able to get a 5x turnover with 3/4".

Another thing to consider is the size of the drain bulkhead and the type of overflow you have. If you're running a durso and only have a 3/4" drain, then you might only be able to get ~400gph through it, 600gph if it is 1", and neither will support a 5x turnover (conservatively). A 1" or larger herbie/bean would be able to handle 5x.

 

[ca1ore]

Depends a lot on the chiller (cooler?) you use. Most are significant areas of flow loss because they use inexplicably small native plumbing. There are exceptions. My TradeWinds is native 1 1/2” (part of the reason I chose it). COR is not great against back pressure, so depending upon the net flow you want the chiller night need it’s own dedicated pump. Either way, maintaining at least native plumbing for the COR should help a lot. Even with a pressure rated pump, I saw a significant increase in net flow when I dumped 3/4” vinyl tube for 1 1/2” flex pvc.