Balancing dual return pumps

[benapilot]

Hello everyone!

I’m in the building/plumbing phase of my new 150 gallon build. I plan on having dual return pumps, one for each return bulkhead in the tank. I’ll have a COR20 running through 3 90’s and a manifold (currently just a carbon reactor), and a COR15 going through two 90’s. I’m running a bean animal overflow with 1” drains.

Questions for the community:
1- How hard/easy will it be to balance the flow from each?
2- Should I get a couple flow sensors, or will that add a level of unnecessary complexity and/or points of failure? My thought is to put them just before the check valves so I know exactly what the flow into the tank is.
3- If I put a flow sensor in, does the apex have the ability to keep the flow constant by controlling the COR output? I.e. As my carbon reactor gets clogged and flow reduced, more will be going to the display- it would be nice if the Apex could adjust the COR output to compensate.

*plumbing is still mostly dry fit without any supports, etc.

 

[AlexG]

If both return pumps are not sharing plumbing lines then the only limitation is the overflow capacity. I would be reluctant to try and program pumps to compensate for one failing as it just another potential point of failure that can possibly lead to a flood. The easy and least risky method would be to set both pumps the the maximum level of flow they can provide without overwhelming the overflow. That way if a single pump fails it will just slow down the flow to the sump.

 

[User1]

I run a similar setup. Cor 20 on the return line with the longest patch Cor 15 on the one that is shorter. Both are matched up to 1" sea swirls. Bean Animal overflow. Drains are 1" in the box due to space but bulkhead plumbing to sump is 1.5". Bean Animal design is only limited by the return pumps and flow if setup properly which gets back to the overflow, plumbing, and return pumps.

Also with this config I have a Cor 15 on my skimmer. Easy to swap out pumps due to all using same fittings should one fail as I don't need the skimmer. I do need the return. Also Cor 15 is plugged into an energy bar bus whereas the Cor 20 is on its own outlet outside the energy bar. Lots of redundancy here.

Your questions:

1- How hard/easy will it be to balance the flow from each?

- I've never had balance issues even when using the Cor 20 and 15. They are not using the same power in my case. The Cor 20 is running at 40% and the 15 is at 60%. The key is the sump water level. So just know they may not be the same levels. The only difficultly I had was trying to implement the intelligent flow thingy - I forget the name. Feed mode I guess also which reduces flow to barely eclipse the overflow weir. I don't use it so not a big deal.

2- Should I get a couple flow sensors, or will that add a level of unnecessary complexity and/or points of failure? My thought is to put them just before the check valves so I know exactly what the flow into the tank is.
3- If I put a flow sensor in, does the apex have the ability to keep the flow constant by controlling the COR output? I.e. As my carbon reactor gets clogged and flow reduced, more will be going to the display- it would be nice if the Apex could adjust the COR output to compensate.

- I do not use flow sensors so will pass. To me it is added complexity and I'm not concerned with it in my use case. However, I know many hobbyists like them for various reasons. I've just not implemented one. Again to me it is related to flow and what your belief is on turn over. Slower to let the skimmer process more water or fast to generate more flow in the display and move water around. Both are valuable and do not need meters. They are a tool to possibly show numbers (important) and possibly alert to maintenance or error. Can somewhat be done without using other methods in Apex.

 

[Brett S]

The short version is that it doesn’t matter if the flow is balanced between the two pumps. You could have one at 10% and one at 100% and everything would work fine.

That said, since the water is entering your tank at opposite sides there is probably some benefit in making sure that a decent supply of new water is coming in on each side just to help keep the water flowing and to minimize any dead spots. But there is certainly still not a requirement to match the flow for this. If one pump is providing 40% of the flow and the other 60% then you will still be good.

I have two COR20’s and one has a longer plumbing run than the other, so the output is not the same when they run at the same speed. I made a minimal effort to balance the flow by just feeling the water coming out of the returns and trying to get them to the point where they both felt to have about the same amount of pressure. I have no idea how close they actually are, but it doesn’t really matter.

If you wanted to go overboard you could certainly get the FMK and there might be other benefits to having that (you could tell if a pump had stopped or the output was reduced) but I certainly don’t think that’s necessary.

 

[benapilot]

Thanks guys! That's exactly what was going through my mind...
Good to have input from people with first-hand experience!!

 

[schuby]

I run two Cor20s with fully independent plumbing on my 150 gal DT with 30+gal sump. No manifold. I have a 1" flow-sensor on each (union: flow-sensor: union). Unions and flow-sensors will effect the overall flow, but I consider them critical. Unions for the ability to remove/replace things such as pumps or flow-sensors (and disassembly if moving tank). Flow-sensors so that I know that the pumps are functioning, how much flow, and when I need to clean my pumps. I also have a ball-valve on each return line after the flow-sensors so that I can perform maintenance on one pump or flow-sensor while keeping the other pump running. I've had a pump-controller fail and just closed the ball-valve until it was replaced, running on one pump: my primary reason for having two, independent return pumps.

I balance the flow by adjusting the power of each pump. One pump goes through my chiller and has the shortest route to DT: it runs at a higher setting of 65%. The other has the longest route to DT: it runs at a lower setting of 43%. They each are set to give me 300gph. I can't get too much more than that from the first pump, due to the chiller and all the additional fittings (mostly 3/4" pipes). I have no concern that they be exactly equal: 290 and 310 is still 600gph total. I've found that running the two pumps with more water above them (depth of water in sump chamber when running normally) gives better flow for the same power.

For me, I set the IQ-level min/max to 1/100. If they aren't this way, then 0 isn't really zero and 100 isn't really 100%. When you set the power-level of a pump, it is relative to the min/max of the IQ-level. I have non-mechanical, anti-siphon fittings on both returns in DT so I turn my pumps off when feeding. I also want the little bit of daily back flow to help with my chiller maintenance.

If you do add flow-sensors, keep them above the water-level at all times, including when pumps are off. They are not necessarily water-proof and the screws will rust a bit.

If those are one-way valves on your returns, I recommend installing unions that will allow you to remove and clean them periodically.

 

[benapilot]

I have a 1" flow-sensor on each

Slightly off topic @schuby, but how are your flow sensors doing? I see very mixed reviews on BRS and don't want to introduce a potential point of failure in the system, yet knowing what my actual flow numbers are would be nice...

If those are one-way valves on your returns, I recommend installing unions that will allow you to remove and clean them periodically.

My check valves are union check valves, so they should be easy to maintain.

 

[schuby]

I bought the original flow-sensors in 2018 (bought everything over the year). I wasn't aware that they weren't water-proof and my stack (pump > union > flow-senser > union > bib-for-short-piece-of-flexible tubing) put the bottom half of each flow-sensor in the water when pumps are off (only because I didn't make it higher when cutting/fitting pipes). After about 8 months of running and a long power-outage (6-7 hours), one of the flow-sensors stopped reporting. I took it apart and found the inside circuitry was wet (and poorly sealed). I bought two new flow-sensors in late 2019 and replaced both. The new ones are sealed much better (v2?). I've had a few power-outages since and have not had any issues. The lower screws rust a bit, but not excessively. If it were to happen again, I would replace them and probably adjust the height (which means buying two more special Neptune unions due to weird threading on pump).

I consider the flow-sensors critical due to past experience with my first, 90-gallon tank (2004-2015). Something like 15 years ago, I left the pumps off overnight after feeding phyto (lights off) and lost almost all my fish, including several full-sized tangs. It was terrible. Now I always check that there is flow occurring on Fusion right before going to bed. I also use the Apex feed-mode to turn things off because it always turns them back on (my first tank used a power-strip with a switch to turn pump/chiller/skimmer on and off).

 

[schuby]

The one thing that I would have done different with this second tank is that I would've used some actual Live Rock from one of the few online places. https://www.reef2reef.com/threads/live-rock-source.781426/

My first tank was all live rock. It was amazing. I knew nothing about salt-water tanks and it grew LPS and SPS wonderfully. For my second tank, I read on sites like this one that dry-rock with bottled bacteria was the same. I didn't know that the people making these statements had never used live rock and didn't know the difference. Shame on me.

There is a huge difference. Everything takes much longer and is more fragile. I would have saved a lot of money, time, and frustration by investing in some live rock. 100% probably isn't needed, but would be the most ideal.

Hands down, that is the best advice I could give anybody.

 

[benapilot]

I’ll be transferring about 70 lbs of live rock and a couple dozen marinepure balls from my current tank. I agree, real live rock is the way to go. I got “the package” from Tampa Bay Saltwater on my last go around and it was AMAZING!! Hopefully he’ll be up and running again by the time I’m ready to get this new build going (stupid COVID!). If I can’t get TBS, I’ll grab some choice pieces from the LFS cycled rock vat.

 

[Crustaceon]

You don’t have to balance the flow as it all gets equalized in the drain. You could run twelve different gph return pumps on seperate return lines and the drain flow would just reflect the cumulative flow from those pumps entering the display.