going with closed loop

[T1tan360]

hey guys i was wondering if this will work i have an overflow that covers the whole back of the tank. i was wondering if i could put my intakes for the closed loop pump in this overflow chamber? to give you an idea i drew something in paint really quick first drawing is a side view and the second drawing is if you were staring at the back of the tank.

 

[Krish]

I'll look back and see if I can find an old thread of mine probably about 6 years old where I asked the same question and I believe it was Mojo who said that it wouldn't be considered a closed loop and that it wasn't too good of an idea. Let me double check though. One potential problem I can see with it is you are relying on an overflow for your sump drain and to feed your "closed loop" so you will have to make sure your sump drain and your "closed loop" pump doesn't exceed what your overflow can handle. Also, you will have to make sure the water level in the tank doesn't drop too low as it will effect the overflow flow flow rate which could be another problem. I did a false wall in a 10 gal tank where I had water drain over the DIY overflow into a compartment where I had some maxijets in there to return flow back into the tank through some lockline. When I water tested it, I almost drained the compartment as the pumps were too much for the overflow to handle. To fix it I had to extend the length of the teeth for the overflow so that it could handle more flow. This fixed the problem, but I was left with an issue that I had to make sure the water level didn't drop too much. If it did, then the pumps would exceed what the overflow could handle and I'd end up right back to where I was with too much flow for the overflow to handle so this is where you have to be careful. Almost similar to how an all-in-one nano is. The have the return pump sitting in the back compartment where it gets water from the tank the overflow that drains back there. The pump is too big or water level drops too low and you have a problem. If you notice when people do closed loops, their suction is usually drilled low in the tank.

Anyways, let me look for that link real quick.

 

[mojoreef]

Nope you cant put the intake in the overflow, you end up shooting bubbles into your tank because the overflow can handle the closed loop pump. Do you have a picture of the tank??

Mike

 

[Krish]

It's kinda different than yours, but I was still advised not to do it this way by Mojo. Post #29 http://www.reeffrontiers.com/f14/diagram-closed-loop-glass-tanks-10424/index2.html . I actually had a diagram there that was basically what you have there, but with the closed loop pump sucking through the overflow wall. Anyways, you'll see what I mean by it.

 

[T1tan360]

I don't see how it's not a closed loop it's a dedicated intake and output in the same tank for a closed loop. It's not running off of the overflow drains.I don't see how it would change the water is going to stay in the same tank the overflow is a 40g volume. It just recirculating it from the back to the front. I have seen people put their intake for their closed loop in their overflow . I had a buddy do it with a mag 9 had the intake tube go up and over the back glass into the overflow and the outputs were up and over the back glass no drilling.

 

[Krish]

I don't see how it's not a closed loop it's a dedicated intake and output in the same tank for a closed loop. It's not running off of the overflow drains.I don't see how it would change the water is going to stay in the same tank the overflow is a 40g volume. It just recirculating it from the back to the front. I have seen people put their intake for their closed loop in their overflow . I had a buddy do it with a mag 9 had the intake tube go up and over the back glass into the overflow and the outputs were up and over the back glass no drilling.

What i gather going by your diagram is it will be running off of the overflow drains because that's how water gets to the pump (by spilling into the back compartment where the pump sits and sucks water from). Technically, what the pump sucks in it will push out which would keep water level constant only if...Your overflow can drain water at the same rate the pump is sucking in water. If the overflow can't handle it along with the sump drain, then you will start pumping more water into the tank from the back compartment alot faster than it can drain back there. As a result, you empty the back compartment and overflow the tank. This is one reason why it's not a true closed loop. A true closed loop wouldn't be affected by this as it sucks water directly out if the main display and puts the water right back in there without anything in the way essentially working as a closed system.


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[T1tan360]

well im not sure if that will work but i dont want to risk it either and have to totally redesign the tank after the all the plumbing test are complete and having to patch holes because it didnt work. so i thought about doing this. i also didnt draw in the overflow plumbing to the sump and refugum because i didnt think its relative to this

these are obviously not to scale. my concern for this one is the intake screen on the right side of the tank making 2 90 deg and then a long 5' run to the pump will cause cavitation? not sure though i never ran a closed loop and from searching the countless threads all of the net this is what i can come up with. i just didnt want the intake screens in the tank

 

[Krish]

That one looks a lot better as you will be sucking directly from the tank. The fact that you are using two suctions leaves me to believe that you shouldn't have an issue with the two 90 degree bends and the 5ft run on that one suction. I guess someone like Mojo will have to confirm that to be 100% sure. One suggestion I'd make would be to put a ball valve (or two) of some sort on the output for the closed loop to tweak the flow on the two outputs some. When I did a closed loop on my 38 gal the first time around, I had 2 suctions and 4 outputs coming from a single closed loop pump. What ended up happening was the fact that all of the plumbing wasn't the same length and some had more bends than others etc. I had a lot of flow out of some of the outputs and very little out of the others. I put lockline ball valves on all of the outputs first because I didn't want to chop up the plumbing which worked as I was able to fine tune the flow exactly, but it was very bulky and very ugly in the tank so I ripped out the whole closed loop and re-did it using two pumps instead. I figured since I had to re-do it, I may as well add another pump for more flow. However, if I kept just the single pump like you will be using, the plan was to plumb two ball valves on the back of the tank and fine tune the flow from there.

 

[T1tan360]

yeah im going to put ball valves on and quick disconnect unions so i can take it all apart. and change it if i need to

 

[TheKraken]

It is a bad idea to mix an overflow (sump) with a closed loop in the same chamber. During a power outage the closed loop will try to fill the overflow and the sump will try to empty the overflow... If you were not planning on using the sump you could make an "all in one" where powerheads and pumps live in the former overflow box and an auto top of system makes up for evaporation.

Post #7 looks better but I would move the returns up so that you can drill a siphon break. Check valves are not 100%.

I will be running a "closed loop" with a submersible return pump in the aquarium. I have to hide a power cord and some plumbing but it should be efficient and serviceable.

 

[T1tan360]

It is a bad idea to mix an overflow (sump) with a closed loop in the same chamber. During a power outage the closed loop will try to fill the overflow and the sump will try to empty the overflow... If you were not planning on using the sump you could make an "all in one" where powerheads and pumps live in the former overflow box and an auto top of system makes up for evaporation. QUOTE]

i dont see how the closed loop will try and fill the overflow chamber when the power is out. and if i have a check valve on the return pump output and one on each 1" i should be good. i have been using check valves since i started reefing and never had an issue. i do see that they will compete for the water in overflow chamber but as long as the return pump is larger the than closed loop pump it would be okay or shoud it be the other way around?

i am using a sump 48"x24"20T and the tank is 5'x3'x2'T and a seperate 40g breeder for the refugium. overflow chamber has 6 bulkheads in it 3 1" and 3 3/4". all the 1" drains into a 2" line that is going straight into the skimmer section and all the 3/4" bulkheads are the dedicate line with valve to control the flow for the fuge.