40B — Single- or Dual-Return

[nickkohrn]

I am in the process of planning a stand-alone frag system that will consist of a 40-gallon breeder tank and a sump. I will be using a Modular Marine external overflow box, and I will be plumbing a 1” Bean Animal configuration.

Would it be better to drill one bulkhead or two bulkheads for return plumbing?

If it makes any difference, I will have two EcoTech VorTech MP40wQD pumps for movement as well as a Neptune Systems COR-15 for the return pump.

Thank you!

 

[arturoo1977]

Not an expert here, but I like more two returns for better water movement. Although you will have more connections and “points of failure”.

 

[Reef-junky]

You really only need one.

 

[TDEcoral]

I have a similar set up. One return is fine, you don't really want to rely on the return for water movement anyway. The mp40 will give you more water movement than you need. Also, 1" is overkill for the overflow. I wish I had gone with 3/4".

 

[nickkohrn]

I have a similar set up. One return is fine, you don't really want to rely on the return for water movement anyway. The mp40 will give you more water movement than you need. Also, 1" is overkill for the overflow. I wish I had gone with 3/4".

Why do you think that 1” is overkill? Have you had issues caused by using 1” plumbing?

 

[lpsouth1978]

I have done both 1 return and 2 in a 40b and in the end, I prefer the single return in a tank this size. Either works well, just my personal preference.

 

[nickkohrn]

I have done both 1 return and 2 in a 40b and in the end, I prefer the single return in a tank this size. Either works well, just my personal preference.

Do you mind sharing why you prefer a single return?

This will be the first time for me to drill a tank and plan plumbing outside of reef-ready tanks. I want to ensure that I make an informed decision, so your thoughts will be quite helpful.

 

[TDEcoral]

Why do you think that 1” is overkill? Have you had issues caused by using 1” plumbing?

To clarify, it depends on the flow rate through the sump. Unless you're just slamming water through the sump and overflow at a high rate, the gate valve has to be closed pretty far because much of the flow capacity of the 1" is not being utilized. 3/4" is plenty capable of handling a "normal" rate of flow through the sump. I'm in the process of setting up a 75g and I plumbed it with 3/4".
This is just my personal experience and I hope I explained it adequately.

 

[nickkohrn]

To clarify, it depends on the flow rate through the sump. Unless you're just slamming water through the sump and overflow at a high rate, the gate valve has to be closed pretty far because much of the flow capacity of the 1" is not being utilized. 3/4" is plenty capable of handling a "normal" rate of flow through the sump. I'm in the process of setting up a 75g and I plumbed it with 3/4".
This is just my personal experience and I hope I explained it adequately.

That does make sense.

The tank will house only SPS corals, so I do plan on running a lot of flow through my sump to aid in filtration since I like to feed heavily.

Thank you for your explanation — I appreciate it.

 

[Huff747]

I used a single return on mine. Drilling for 2 returns means doubling your chances of cracking the tank while and unless you are running 2 return pumps I found trying to plumb 2 returns from a single pump to be annoying and you end up with different flow out of the two unless you can duplicate the plumbing to both.

I think most of the in tank flow is done by powerheads so all I really used my return for was to get the water back into the tank.

 

[Phildago]

One return is more than enough. I Have a relatively small pump and I don't even have it on full blast because I get plenty of turnover as it is. If you were worried about flow I guess you could add another, but it's much easier to just add an extra wave maker for flow

 

[Reef-junky]

You should not be using the return pump for flow in your tank.

 

[nickkohrn]

You should not be using the return pump for flow in your tank.

I agree, and that’s not my intention. I have two MP40s that will be providing intense flow.

 

[lpsouth1978]

Do you mind sharing why you prefer a single return?

This will be the first time for me to drill a tank and plan plumbing outside of reef-ready tanks. I want to ensure that I make an informed decision, so your thoughts will be quite helpful.

2 returns was a lot more difficult to tune. One always had more flow than the other. I also did not like how much space was limited by having the overflow box AND 2 return lines in the tank. Finally, there is more plumbing involved with 2 returns and more chances for leaks/issues.

If I was doing a 48"+ tank, I would still go with 2 returns to maximize turnover, Though I would probably use 2 return pumps as well. With a 36" tank it is just not needed. Even the Red Sea 750XXL only has a single return on it.

 

[Reef-junky]

You really only need two returns in a big tank well over 100gal.

 

[dhof]

I have a 40 Breeder with a sump as my main DT. I drilled a return into it, and then had 2 RMAs on my pump. This third pump works fine, but I learned my lesson on redundancy, and I installed a 2nd pump. I have flow monitors on both return lines so it is dead simple to adjust the combined flow to exactly match my overflow.

I haven’t touched the valve on my overflow basically since I set it, since I can keep the flow exactly the same based on the flow sensors.


Since I already had the tank drilled for the first return, I had to do the 2nd return over the top. I love the over the top return and hate that I drilled the first return. If I had to do it over again I would take both returns over the top instead of drilling the returns. Using the Red Sea screen kit I am able to tightly cover the over the top pvc, and they are way more out of the viewing area than the drilled return is.

Whenever I unscrew the unions somewhere on my drilled pvc rerun I cringe thinking the vibration could break the glass up there but I have no such cringing when manipulatingthe over the top return line.

 

[dhof]

here’s a pic of how small the over the top footprint really is.

another thought on dual vs single is: you are putting a bean animal overflow on the tank. Bean animal is awesome, and it’s design is awesome because it is very redundant. Seems like redundancy is important to you, so why invest in redundancy in the overflow, but then put a single point of failure with only a single return? Just pointing out that if redundancy is important enough to warrant a bean animal it’s probably important enough to warrant a 2nd return line too.

 

[samnaz]

Two MP40s will provide enough flow on their own. I see no reason for dual returns.