Dual Return Pumps

[xxjt2oxx]

I have a 220g in wall tank - long story short I replace a 150g that was previously there and increased the front to back depth of the tank by moving the back wall. Since it went back in the same place, there were a few challenges getting all the plumbing in and there are a few more fittings than would have been ideal.

That all being said, I'm running a Cor20 and I just don't feel like I'm getting enough flow through the sump. I've always liked the idea of dual return pumps, but didn't consider it a possible necessity until now. I have 2 questions -

#1 - My tank has 4 return lines, one in each corner at the top of the tank. Currently the front 2 and back 2 are tied together, and then those lines tie together before continuing down to the return pump. Each individual return to the tank has it's own ball valve. Is it as simple as connecting 2 pumps as easy as Pump -> Check Valve -> Y -> existing return Line?

#2 - $450 for a return pump was fine when I was relying it to be my lifeline, would switching to a cheaper brand DC pump be OK now since I have a fail safe? For less than the price of a COR20 I can buy 2 new pumps plus 2 back ups to keep on hand.. is that a bad idea?

 

[Saltyreef]

Do you have more than 5 feet of head height from your sump to your tank?

If not, i would say your Cor20 is adequate. You are rated around 9x turnover with it and that should be plenty sufficent for anyones needs. I would keep a spare jebao DC pump as backup for emergencies.

Also, you shouldnt need any check valves on the returns if you are running a standard overflow, sump and surface return style system if properly setup.

 

[UncommonSense]

I'm running a Cor20 and I just don't feel like I'm getting enough flow through the sump

What is the plumbing diameter coming off this pump? It sounds like you’re either splitting this pump’s output too many different directions, or the plumbing is restricting flow!

Is it as simple as connecting 2 pumps as easy as Pump -> Check Valve -> Y -> existing return Line?

Assuming both pumps have serviceable check valves (which you actually maintain), and the plumbing is sized correctly for the target flow rate, yes!

 

[xxjt2oxx]

Hard to explain but hopefully it makes sense.

The return pump is a 1” barb to 1” silicone tubing, to a 1” barb on a 1” pvc tee. From the tee it’s 1” to a 1x3/4x3/4 tee, which comes out at 3/4” and goes to each of the 4 returns.

 

[areefer01]

I have a 220g in wall tank - long story short I replace a 150g that was previously there and increased the front to back depth of the tank by moving the back wall. Since it went back in the same place, there were a few challenges getting all the plumbing in and there are a few more fittings than would have been ideal.

That all being said, I'm running a Cor20 and I just don't feel like I'm getting enough flow through the sump. I've always liked the idea of dual return pumps, but didn't consider it a possible necessity until now. I have 2 questions -

#1 - My tank has 4 return lines, one in each corner at the top of the tank. Currently the front 2 and back 2 are tied together, and then those lines tie together before continuing down to the return pump. Each individual return to the tank has it's own ball valve. Is it as simple as connecting 2 pumps as easy as Pump -> Check Valve -> Y -> existing return Line?

#2 - $450 for a return pump was fine when I was relying it to be my lifeline, would switching to a cheaper brand DC pump be OK now since I have a fail safe? For less than the price of a COR20 I can buy 2 new pumps plus 2 back ups to keep on hand.. is that a bad idea?

2 returns = redundancy should one fail. Brand type doesn't matter until we are talking budget. Having run 2 return pumps, both happening to be Cor's (I also run one on my skimmer) I treat them as individual lines. They are not connected.

I personally would match. Whichever brand you go with, match.

 

[UncommonSense]

Hard to explain but hopefully it makes sense.

The return pump is a 1” barb to 1” silicone tubing, to a 1” barb on a 1” pvc tee.

Aha! There’s your problem!

— 1” barbed fitting Inside diameter:

— 1” schedule 40 PVC pipe inside diameter:

This said, your plumbing is really hurting your pump’s maximum output potential…

— refresh my memory? Does the Cor-20 come with a pump outlet adapter for 1”-1.25” PVC pipe, or 1.25” barbed?

 

[KrisReef]

Look into flexible PVC pipe used for hot tubs. It is more expensive than flex hose but it doesn't sacrifice the inside diameter and the difference between 1 and 3/4 inch diameter flow rate maximums is significant for these applications.

 

[areefer01]

— refresh my memory? Does the Cor-20 come with a pump outlet adapter for 1”-1.25” PVC pipe, or 1.25” barbed?

I forget the specific parts but pretty sure it includes 1.25" BSPP > 1.25" Slip Union and 1.0" & 0.75" Slip Fittings.

I would not reduce but if one has to, do so at the end point. Not at the pumps outlet. That will wreck performance as you noted.

 

[mcarroll]

That all being said, I'm running a Cor20 and I just don't feel like I'm getting enough flow through the sump.

It will help if we're emprical....what flow rate do you want?

From googling, it looks like under typical conditions the COR20 might deliver something like 1200-1500 GPH.

https://inventory.powerzone.com/resources/friction-loss-calculator/
In that friction loss calculator, I estimated 3/4" plumbing for 20GPM (1200GPH) with 10 ft of plumbing and 4 typical fittings. That combo appears to generate +10 ft of head pressure....so instaead of your pump having to overcome just the 5-6 feet of vertical height from the sump to the tank, it's as if there were 15-16 feet to overcome.

According to google, your pump would deliver about 400 GPH under those conditions.

Two pumps is not an answer. Re-plumbing would be the ticket to unlocking the current pumps potential.

That or switch to a smaller pump (to reduce investment and save power) and just adapt to the plumbing and flow rate you have.

By far easier to adapt; by far better to change the plumbing.

 

[xxjt2oxx]

It will help if we're emprical....what flow rate do you want?

From googling, it looks like under typical conditions the COR20 might deliver something like 1200-1500 GPH.

https://inventory.powerzone.com/resources/friction-loss-calculator/
In that friction loss calculator, I estimated 3/4" plumbing for 20GPM (1200GPH) with 10 ft of plumbing and 4 typical fittings. That combo appears to generate +10 ft of head pressure....so instaead of your pump having to overcome just the 5-6 feet of vertical height from the sump to the tank, it's as if there were 15-16 feet to overcome.

According to google, your pump would deliver about 400 GPH under those conditions.

Two pumps is not an answer. Re-plumbing would be the ticket to unlocking the current pumps potential.

That or switch to a smaller pump (to reduce investment and save power) and just adapt to the plumbing and flow rate you have.

By far easier to adapt; by far better to change the plumbing.

This is what I’m leaning towards, but unfortunately due to the locations of everything in the wall I cant really plumb it any differently that would be helpful.

Using 2 pumps, if ran 2 separate loops, I would eliminate one 1x1x1 tee, that’s the only fitting I can remove.

Flow wise I’m looking to be able to push 2000+ if I want to, but ultimately probably run around 1400-1600

 

[UncommonSense]

This is what I’m leaning towards, but unfortunately due to the locations of everything in the wall I cant really plumb it any differently that would be helpful.

Using 2 pumps, if ran 2 separate loops, I would eliminate one 1x1x1 tee, that’s the only fitting I can remove.

Flow wise I’m looking to be able to push 2000+ if I want to, but ultimately probably run around 1400-1600

You can simply switch to 1.25” tubing and barbed fittings between pump and 1” rigid PVC to net a massive flow improvement on existing rigid PVC plumbing!

 

[mcarroll]

Well, you can get about 400GPH from each leg of your return if you run two pumps.....800 GPH total, maybe 1000. Just need two smaller pumps that generate about the same pressure as what you have. (Smaller COR pumps might be the ticket.)

What about new plumbing over the back of the tank?

Also consider that the general advice is that 1-5x your display size will be adequate sump flow for most tanks. E.g. a 200 gallon tank only needs 200-1000 GPH. Meaning that even 200 GPH will do the trick.

Just an example, I don't know the size of your tank. Maybe you don't need to shoot for 2000GPH?

 

[UncommonSense]

I estimated 3/4" plumbing for 20GPM

Let’s keep in mind that the current rigid PVC return plumbing layout begins at 1” then employs a reducing tee to get two 3/4” outlets!

The return pump is a 1” barb to 1” silicone tubing, to a 1” barb on a 1” pvc tee. From the tee it’s 1” to a 1x3/4x3/4 tee, which comes out at 3/4” and goes to each of the 4 returns.

If I’m understanding OP plumbing layout correctly, the current bottleneck is the ID of 1” barbed fittings associated with the 1” tubing!

 

[BuffaloLake]

I run dual Cor 20’s. Sump is 2’ directly below the tank. I shoot for 10x turnover. When I first set up my system I hard plumbed everything with 3/4” using 90’s. Each return line went through UV, with seven 90• elbows on each line. My Cor 20 pumps would max out at about 45%. I re -plumbed everything, eliminating 3 of the 90’s on each line, and replaced the remaining 90’s with 45’s. Now the pumps max out around 85%. Your Cor 20 might not be moving as much as you think.

 

[xxjt2oxx]

You can simply switch to 1.25” tubing and barbed fittings between pump and 1” rigid PVC to net a massive flow improvement on existing rigid PVC plumbing!

All things said that’s a pretty easy fix - going to order some parts and start here!

 

[xxjt2oxx]

Well, you can get about 400GPH from each leg of your return if you run two pumps.....800 GPH total, maybe 1000. Just need two smaller pumps that generate about the same pressure as what you have. (Smaller COR pumps might be the ticket.)

What about new plumbing over the back of the tank?

Also consider that the general advice is that 1-5x your display size will be adequate sump flow for most tanks. E.g. a 200 gallon tank only needs 200-1000 GPH. Meaning that even 200 GPH will do the trick.

Just an example, I don't know the size of your tank. Maybe you don't need to shoot for 2000GPH?

So the issue with the plumbing is the tank is in the wall and divided 2 rooms, so there’s no over the back - I only have the ends to work with.

That also means my overflows are on the ends, and with the amount of water I’m moving now you can visibly see how much stuff misses the overflow because there isn’t enough flow.

The tank is 220g so I’d like to be able to turn over close to 10x if I want, although I don’t see it as neccesary

 

[UncommonSense]

The tank is 220g so I’d like to be able to turn over close to 10x if I want, although I don’t see it as neccesary

Off 1” sch.40 PVC plumbing?

You’ll likely be able to hit ~6-8X turnovers… more than that, and you start burning power/making a lot of waste heat, or needing bigger plumbing!

 

[Grog]

2 returns = redundancy should one fail. Brand type doesn't matter until we are talking budget.

I have two returns for this exact reason. One clog or one failure and the entire system isn't failing.

Redundancy is a good thing with reef tanks.

 

[mcarroll]

So the issue with the plumbing is the tank is in the wall and divided 2 rooms, so there’s no over the back - I only have the ends to work with.

That also means my overflows are on the ends, and with the amount of water I’m moving now you can visibly see how much stuff misses the overflow because there isn’t enough flow.

The tank is 220g so I’d like to be able to turn over close to 10x if I want, although I don’t see it as neccesary

Are the ends of the tank the parts that are "in wall"? No way to go over the overflows?

Eliminating the 3/4" run will help, but 1" is just a lesser problem.

Revising my calculator estimate from earlier to use 1"still gives +5 feet of head pressure.

May not get the target flow with 1", but seems like it should still be enough.

It would also be interesting to me if you were to measure your actual flow rate now before making any changes. Calculations and estimates are nice, but...it's nice to know for sure sometimes. How much flow are you really currently getting?

 

[areefer01]

May not get the target flow with 1", but seems like it should still be enough.

Worth mentioning that the outlet on the Cor 20 is 1 1/4" (1.25") threaded outlet and is recommended for maximum flow and efficiency. You already know about reducing so no need for me to repeat.

I run my Cor 20 with 1" pvc but accept the slight decrease in performance.