Tank Return Flow

[Phil]

Hi everyone, I'm just setting up a new system and wanted to run a few things by some of the experienced members. Here are some details.

Tank 100 gallons
Sump 45 gallon Primo Reef Acrylics with 3 sections.

Distance from return pump outlet to tank inlet (approximately 60 inches)
Return hose diameter 1 inch with 1 45 degree elbow and 1 90 degree elbow
Overflow pipe 1 inch main with 1 inch emergency pipe with gate valve set to keep overflow quiet. 2 x 90 degree elbows on each pipe
Center mounted internal trapezoid overflow
Tunze 1073.05 running at 18v with mechanical intake dial set wide open and variable dial set wide open. This gives 581 gph and the max head height at 18v is 98 inches.

Turn off skimmer
Turn off return
Wait till overflow has stopped
Feed fish
Wait about 15 minutes then turn on return
While return is filling the tank again, the level in the return section of the sump gets low enough that the return pump will draw a bit of air and the Tunze ATO will kick in trying to keep that chamber level. If I do nothing the ATO will run for a few minutes to get that section level. This is not good as we don't need all that RO water added to the system.

The only way I currently can avoid this from happening is have a small jug handy and when I see the return section level dropping close to where the ATO would kick in, I fill up the jug and poor it into the return chamber. I've struggled with this in my head as my last system (same sized tank and sump) used a much stronger return pump and 1.5 inch overflow pipes. Would love to hear your ideas folks. Thanks.

 

[theyangman]

Leave the skimmer and return running during feedings.

the debate rages on pros and cons for the shut off of the return and skimmer during feedings. I personally leave it running because I am lazy. I see no ill effects.

I bet 90% of the guys on here leave it all running. What you MIGHT want to do is turn off your powerheads during spot feeds of corals because they can't move and catch food that flows away from them. The fish however are pretty damn fast and catch all my food before it has a chance to settle anywhere. If you notice extra food lying around, you are feeding too much.

 

[Pistol]

have you got siphon breaks on your return line, sounds like you are siphoning water out of the tank causing the tank level to drop too much.

 

[Phil]

Pistol - I have 1/4 inch John Guest shut off valves on both the main drain and emergency. The valve on the main drain is about 75 percent closed and on the emergency drain it is wide open. TheYangMan - I've always turned of the return when feeding. Keeps all the food in the tank (very lightly stocked) and not in my filter socks.

 

[AdInfinitum]

So is the "missing" water accumulating in an overflow box until the full siphon gets going again, at which point it runs at a lower level?

If your return section is small could you put the ato in a larger section? It would give the FW more time to mix before going into your DT as well.

 

[Phil]

The level rises in the overflow box until the siphon gets going and then in a bit the return section runs low. The return area is about 8 inches wide x 18 inches long and maybe 7 inches deep.

 

[theyangman]

adding any extra water unecessarily will only serve to dilute his salinity though. Seems like a bad idea. Especially since this is going to be an ongoing thing.

 

[theyangman]

I can't imagine that if you are as lightly stocked as you claim you are, and depending on how much food you dump in there, that very much if any really gets sucked into the overflow and ends up in your filter socks. Unless you overfeed like crazy. the amount would be marginal IMO. And any amount that does end up there is a much more prefered option than having to fix this current issue with the water levels.

 

[Phil]

There are only 3 fish right now and I don't feed heavily ( a very small pinch of food once a day). Irregardless though, what if the power was to go out and back on while I am out of the house. A similar situation would arise. I think there must be a simple solution to this that I am just not seeing.

 

[theyangman]

open your drain to 100% why is the main throttled to begin with? Is the sump too small to catch any and all excess in the case of a pump failure? Or is it for noise issues?

edit: I guess if it was for sump issues that would only buy you minutes, so yeah, why is your drain throttled?

 

[Pistol]

I'm saying you may need siphon breaks on your return line not the drains.

 

[Sewerat]

Bean animal system uses the main throttled down until just about not entering the trickle. I'd start by raising your water return pipe a little so it gets its siphon break before it sucks out that much water, will have less to return before system is active. Second your sump might be undersized or you might not have enough water in the system. If you power down everything is sump full to the top when all water stops running? If not you can afford more water in the system. Your ato level maybe is too low? Slightly raise it if you can

 

[jeffopentax]

Having trouble visualizing your setup, but if it's beananimal, try cutting your return flow by half when you start up again. Once it's running you can crank it up again.

 

[theyangman]

Ok, so lets see if I have this straight:

When you turn off your return pump for that 15 minutes, the water in your display tank drains to a point that I am assuming the water level is dropping visably, and falls below the overflow line? So when the return pump when turned back on needs to fill the main display first, then into the overflow which by then the return section of your sump has almost run dry?

IF this is the case then Pistol is 100% correct, you need a siphon break in your return line. What is happening is the returns are sucking water back down into your sump during its off time, and will continue to do so until the return in your display meets the water level and breaks siphon on its own naturally. Depending on how deeply submerged your exits on the returns are in your tank that can back siphon a few inches of water out of the display tank.

 

[Phil]

I'm saying you may need siphon breaks on your return line not the drains.

The return line is barely submerged. I'm having a hard time understanding how having a small hole drilled in the loc-line would help when the return is right near the top of water line in the tank.

 

[jeffopentax]

Having trouble visualizing your setup, but if it's beananimal, try cutting your return flow by half when you start up again. Once it's running you can crank it up again. Should be enough to get your syphon going without draining sump too low.

 

[theyangman]

The return line is barely submerged. I'm having a hard time understanding how having a small hole drilled in the loc-line would help when the return is right near the top of water line in the tank.

The other option is to adjust your baffles so the return section holds more water. Hopefully that buys you enough time to not run that section dry before the returns kick back in and fill the sump more naturally.

 

[Phil]

Bean animal system uses the main throttled down until just about not entering the trickle. I'd start by raising your water return pipe a little so it gets its siphon break before it sucks out that much water, will have less to return before system is active. Second your sump might be undersized or you might not have enough water in the system. If you power down everything is sump full to the top when all water stops running? If not you can afford more water in the system. Your ato level maybe is too low? Slightly raise it if you can

It's a modified 'Herbie' setup. I have the main drain elbow turned down to grab the water entering the overflow box sooner. I am convinced it has something to do with the size of the return pump and drain lines as I stated earlier, I had the same size tank and sump with a waterblaster 5000 running wide open and a modified herbie setup using inch and half pipe for the drains. The sump is not anywhere near the top when everything has stopped as my return fitting sits just slightly under the running water line in the tank. I can raise the ato level switch a bit and try that.

 

[Phil]

The other option is to adjust your baffles so the return section holds more water. Hopefully that buys you enough time to not run that section dry before the returns kick back in and fill the sump more naturally.

I can raise the float switch about an inch and try that.

 

[Phil]

I'll move up the float switch a bit tonight and try that and let you guys know. Right now the water is only dropping about an inch and a quarter into the return area. @ YangMan, how would having a small hole drilled in my return line help ?