Dual Return pumps - dual "swing check valves"?

[RabidDragon]

I'm planning on installing 2 return pumps on my waterbox 220.6 for redundancy purposes. Neptune Cor15's (already purchased). The system was plumbed for 1 return line back to the tank feeding the two return jets in the display tank.

It will be a simple addition of adding a Y tee connector do this however I suspect it would be best practice to add a two "swing check valves" to prevent backflow on each return line from these pumps. In the event of a pump failure this would prevent the water from simply returning to the sump through the failed pump.

Thoughts? Thanks!

 

[MarshallB]

Are you planning on having the backup automatically kick in? If not I would just install 2 ball valves before the Y, then a check valve after the Y. Check valves aren't always a sure thing. Some times they don't seal fully if they get dirty or a snail finds it way in etc. Either way use true union valves.

 

[RabidDragon]

I was planning on having both pumps run at a lower level so if one failed I would have 1/2 the amount of water moving... but that's still 1/2 more than nothing. This would keep the tank going long enough that I would have time to address it.

 

[MarshallB]

I was planning on having both pumps run at a lower level so if one failed I would have 1/2 the amount of water moving... but that's still 1/2 more than nothing. This would keep the tank going long enough that I would have time to address it.

Ah I see. Dual check valve should work then since both will be flowing at all times. I would still install ball valves between the checks and the pumps if you have room just in case. That way you can shut off the flow with certainty if you need to remove one for whatever reason.

 

[theMeat]

Check valves will get crud on them and not work in short order and would need regular maintenance. Would have a spare pump on hand if needed, or run 2 separate lines to tank, one from each pump

 

[RabidDragon]

Humm.... dirty check valves. That's not something I considered. The manufacture build placed a check valve inside the overflow within the display tank. Once assembled I don't know how I would access this to clean it. I suspect the pipe would have to be unscrewed from the bottom of the tank within the overflow leaving a hole in the bottom of the overflow into the interior of the cabinet.

was planning on adding a "Y" tee union on tube "M" to the two return pumps

 

[theMeat]

Imo you’re over engineering with the double pump into one pipe. Just have a spare pump on hand if needed.
Better to drill a hole on return line just below water level inside overflow box to act as siphon break in case of power outage or pump fail. Much more reliable than a check valve

 

[jda]

Two returns are nice if you are not going to be around, but if you are, then I have found it to be worthless. Flow pumps and one heater in the tank (not all in the sump) on a different circuit can keep the tank kicking for a day or two until you can replace one.

If you do not watch your tank often and do require two return pumps, then yes, each point of back siphon will need a flap.

I would keep those check valves in an easier place to service. I have never found them to last long and they do need replaced. I have stopped using them and just did the larger sump and drill-****** just below the water line to break the siphon... these holes can gum up with algae or gunk, but they are easy to clean with a pick.

 

[RabidDragon]

Dual returns: I would be gone for a few days at a time occasionally. How long does a tank survive typically with a power/pump failure.

sounds like both of you (theMeat/jda) would recommend removing the check valve from inside the overflow then?

so with a small pin hole just below the overflow waterline if the power/pump failed the tank would drain into the sump until the water level hit the pin hole?

thanks,

 

[theMeat]

More than a pin hole. Around 1/4” good.
You could take out the check valve or leave it. Just don’t depend on it to save you from a flood.
Once you drill the hole turn off pump to simulate a power outage and see/measure how much water falls into sump before the siphon breaks. Use that measurement to determine max fill line in sump to avoid flood

 

[jda]

If you are going to be gone some, then getting actually reliable equipment is paramount. No DC pump is really all that reliable outside of a Red Dragon or Abyzz. Laguna, Fluval or other Askoll Block Pumps are really reliable with decade-plus type of reliability. They are not cool, but I would take a Fluval or Laguna on a single return over duals of any DC pump under $1000.

Hole size and location will determine how much water will siphon before it breaks. Each situation is different.

 

[RabidDragon]

which AC pump is reliable and the most quiet? and can utilize the apex?

I already purchased the two Neptune COR15's so this would be for the future.

so the 1/4" hole inside the overflow drains the overflow than the main tank drains

 

[ingchr1]

Don't know if it would translat to a sump and the pumps you're using, but on my 40 gallon AIO I just have my dual return pumps plumbed to a Y at the top, no check valves.

When one of the pumps is off there is still flow to the tank. I'm not concerned with the backflow through the other pump, if there is any/much. I still have flow to the tank and no maintenance or failure points associated with having check valves.

The sump level does go high when one pump is off, but the consequences of that are much less than having no flow if you are not around to deal with the issue in a timely manner. Also, pump failures should be infrequent and far between.

I'm running Sicce Syncra Silent 1.0 pumps, for about two years now.

 

[Greg P]

As per drilling the returns to stop the siphon;
I keep my returns only semi-submerged. They stop siphoning as soon as the pump turns off. This is the right side showing 1/2 of my nozzles
I like how it helps with gas exchange and I never hear them

 

[Jeffcb]

Question. Is you concern to as what happens if one pump fails while your away? With those 2 pumps there should be enough head pressure to keep partial flow in you tank if 1 fails without check valves. Test it.

 

[theMeat]

As per drilling the returns to stop the siphon;
I keep my returns only semi-submerged. They stop siphoning as soon as the pump turns off. This is the right side showing 1/2 of my nozzles
I like how it helps with gas exchange and I never hear them

That’s a way to go, except if you bump into em while cleaning or whatnot, and absolutely no harm in having siphon break hole along with this strategy

 

[Greg P]

As per your original question, I see you are trying to stop one pump from going back to the sump in case the other shuts down. Short of running 2 separate return lines - one from each pump - you'll need your initial plan.
You may need over-sized pipe to run both pumps on one return line or you'll lose flow based on restriction.
This can be achieved by using a true union check valve on each pump, as close to the pump as possible for ease of maintenance.
I've used these for at least 8 years and they've never failed, having cleaned them only once so far. All I wanted them to do is keep the return lines filled so there's no splashing in the DT when the pump turns back on, and this worked as planned.
They will work in your case as the valve will slam shut as soon as water backflows from the other pump/both pumps are off.

Don't overtighten them when installing/maintaining. After about 6-7 years I bought replacement silicon O-rings to keep the seals happy, and always use silicone grease to make future dis-assembly easy.
I broke a union fitting on one as the original O-rings became flattened !!

True Union Check Valve - Spears​

 

[theMeat]

And imo Ehiem hobby pump is Ac, quiet, runs cool, and the most reliable pump there is. Not sure if it’s apex controllable

 

[Greg P]

That’s a way to go, except if you bump into em while cleaning or whatnot, and absolutely no harm in having siphon break hole along with this strategy

I wasn't overly concerned about bumping them out of alignment as there were 4 in total so any 1 would do the job.
I won't knock the idea of drilling a siphon hole. I just couldn't get the size correct without spraying, and was concerned about salt creep plugging the hole. I gather regular maintenance would fix that, but my tank ran over 8 years with the above setup without 1 issue.

 

[theMeat]

I wasn't overly concerned about bumping them out of alignment as there were 4 in total so any 1 would do the job.
I won't knock the idea of drilling a siphon hole. I just couldn't get the size correct without spraying, and was concerned about salt creep plugging the hole. I gather regular maintenance would fix that, but my tank ran over 8 years with the above setup without 1 issue.

The holes are just below water level so no salt creep happens. Cheap insurance