Plumbing help

[UncommonSense]

I disagree with this. Even if they are independent the water will still flow back down the other return line acting as a drain right back into the return chamber and just get pumped back up the other return line reducing the amount that goes through the sump filtration.

Have you ever physically tried this before? Or are you disagreeing off theory alone?

Again, you are setting these dual returns up in such a way that they won’t siphon much of any water at all during a pump shutdown… (please read my above response for specific instructions on how to create a reliable siphon break with no moving parts…)

 

[commod0re]

As long as both pumps are running they won’t backflow. Whatever kind of nozzles you have on the outflows will also impede its ability to act as a fast drain in case one is not running. Seems unlikely to me that it would divert a significant volume of water around the filtration. Even without a siphon break and both pumps off it can only drain that way until the nozzles are partially out of the water

how often would you run just one pump instead of both, for an extended enough period of time, for that backflow to even matter enough to worry about? seems like a bike shedding argument to make

 

[UncommonSense]

As long as both pumps are running they won’t backflow. Whatever kind of nozzles you have on the outflows will also impede its ability to act as a fast drain in case one is not running. Seems unlikely to me that it would divert a significant volume of water around the filtration

how often would you run just one pump instead of both, for an extended enough period of time, for that backflow to even matter enough to worry about? seems like a bike shedding argument to make

There is realistic potential for one pump to physically fail, or its electrical circuit to loose power (outage, trip); hence two pumps, on independent plumbing, on separate GFCIs/breakers!

If you had zero return pump shutdown siphon mitigation in place, and your return nozzles were well submerged, it is physically possible for one return pumps plumbing to constantly siphon from the display while the other fills… this isn’t a balanced drain/fill, so it would self-correct eventually, but still isn’t ideal!

— hence me recommending just drilling a small (probably 1/8”-3/16”) hole right around the operating water line in each in-tank return plumbing assembly, letting it “leak” into the display tank during normal operation… this metered leak suddenly sucks in air if a pump shuts down, breaking the siphon almost immediately!

 

[commod0re]

As long as both pumps are running they won’t backflow. Whatever kind of nozzles you have on the outflows will also impede its ability to act as a fast drain in case one is not running. Seems unlikely to me that it would divert a significant volume of water around the filtration

how often would you run just one pump instead of both, for an extended enough period of time, for that backflow to even matter enough to worry about? seems like a bike shedding argument to make

There is realistic potential for one pump to physically fail, or its electrical circuit to loose power (outage, trip); hence two pumps, on independent plumbing, on separate GFCIs/breakers!

If you had zero return pump shutdown siphon mitigation in place, and your return nozzles were well submerged, it is physically possible for one return pumps plumbing to constantly siphon from the display while the other fills… this isn’t a balanced drain/fill, so it would self-correct eventually, but still isn’t ideal!

— hence me recommending just drilling a small (probably 1/8”-3/16”) hole right around the operating water line in each in-tank return plumbing assembly, letting it “leak” into the display tank during normal operation… this metered leak suddenly sucks in air if a pump shuts down, breaking the siphon almost immediately!

Right I agree with that but imo it would be a) noticeable if one pump stops running and its line becomes a drain, and b) probably not as big a problem for the filtration as claimed. So optimizing the plumbing towards solving that problem seems like a waste to me, not just in terms of cost but also in terms of wasting brain power thinking about it

I agree that having a siphon break on there isn’t a bad idea because it’s simple, doesn’t cost extra money, and isn’t a wear part so doesn’t add any additional maintenance or replacement

 

[Jamie814]

Have you ever physically tried this before? Or are you disagreeing off theory alone?

Again, you are setting these dual returns up in such a way that they won’t siphon much of any water at all during a pump shutdown… (please read my above response for specific instructions on how to create a reliable siphon break with no moving parts…)

Yes, I run 2 return pumps on my 500 gallon. Without check valves if one pump is still running and one not, a siphon break won't do much because the water level is still going to be at or above the return nozzles even with just one pump running. With a 6 foot+ drop to the sump it will create a lot of back siphoning right into to return pump chamber through the non-running pump bypassing your filtration. How much will back siphon depends on how far under the surface of the water the return nozzles are. Mine are a good inch under the surface because if they are higher, it causes noise and splashing at the surface.

The other issue can arise is an increased water level in your sump. Depending on how the sump is setup it could cause the skimmer to overflow as well or an ATO to not work correctly. The check valve mitigates this risk as well.

 

[Freenow54]

The Teflon worked! Yes, i agree on the check valve because of what you said. I do have two sicce pumps running, one on each valve. Being a 400g im already nervous enough! Lol

Teflon tape is only considered a lubricant by some. I use a Teflon based pipe dope it does not harden can be taken apart but is sold as a sealant and is a good one but has to be put on dry threads or will ball up

 

[Joeype]

You put teflon tape on the threads? Is it still leak free this morning? I would think doing this would just cause it to leak around the top of the nut then instead of the through the threads?

The designed seal is made with the oring compressed between the two halves. If water gets past that it can leak out through the threads or the top of the nut as there is no seal there.

Its perfect and dry now.

 

[Joeype]

This makes me think there’s a chance that it’s over-tightened and leaking because the o-ring is crushed. O-ring seals need to be tightened a certain amount, too tight and little gaps get introduced

Thought the same thing, tried hand tightening like many of the fittings did....these 2 no such luck. Teflon did the trick perfectly

 

[commod0re]

Glad to hear it!

 

[Joeype]

Glad to hear it!

Thanks and thanks to everyone for always being here with great suggestions, knowledge and information.