What is a closed loop system

[fordtrucksrme]

I have seen several post as to a closed loop system but I am not sure how it works, would someone elaborate as to how the returns that are so low in the tank will keep from emptying it in a power failure??

[cyberchef]

A closed loop system is where you have a pump that draws water from the tank and pumps it directly back into the tank. No open containers, just a pipe/hose connection from the tank (usually via bulkheads) to the pump and then right back to the tank. If the power fails there is nowhere for the water to go and neither end is open to anything other than the tank itself. It is used strictly for circulation of the water, eliminates power heads in the tank, so that you don't try to get the circulation by running the water thru the sump. By slowing the water thru the sump you can help to eliminate micro bubles and the slower rate will allow the sump to do it's job better if you have anything it it for filtration or have it set u[p as a refugium.

[fordtrucksrme]

Thanks cyberchief, I had it in my mind it was just for circulation but wasn't sure. How are micro bubbles damaging?? I always thought it was good to have tiny bubbles as it oxeyginates the water better for better saturation

[fordtrucksrme]

Sorry cyberchef not chief or maybe chief chef.

[cyberchef]

Most people don't like they way the cling to everything and make bigger bubbles.. lol Plus it makes the tank appear "not clear".. But as far as I know they are not actually harmful.

[ShirleyM]

I was advised to use our extra GenX Mak4 1200gph pump as a closed loop for our 120 to add more water flow and less dead spaces. If we do this, how do we keep such a strong intake from killing fish that swim near it? Connect the intake to a pvc bar and make several intake holes? Also, I'd need to put screen over the holes or a snail could plug up the pump, etc.

Thanks,
Shirley

[Geoff]

ShirleyM-depending on the asthetic(sp?) issues putting an old prefilter spong from a PH over the intake would work. also the longer the bar, and the more holes the less the suction would be for unwary inhabitants. on my mag 12 i just have one of those 1" PVC screens i got online from drsfostersmith, i am sure premium has them, but i got it before i knew Jason and PA. I seems to work fine, but right now all i have is a kole tang and he is far to big to be affected.

G~

[ShirleyM]

Thanks, Geoff, I have a few of those prefilter sponges in a bin somewhere...

[cyberchef]

I've also seen pics of where someone used a PVC drain cap to cover the intake so nothing could get sucked in. But yet it was big enough and open enough that it would not clog easily.

[ShirleyM]

Like a circle with holes in it? That would be good - I was just thinking I sure wouldn't want the return siphon to clog - then we'd have a flood! (floods, electricity, shocks, and fires! Don't need any of those!)

[cyberchef]

Holes or slots/slits cut into the round top of the drain cover.

[tdwyatt]

Originally posted by ShirleyM
I was advised to use our extra GenX Mak4 1200gph pump as a closed loop ... ... If we do this, how do we keep such a strong intake from killing fish that swim near it?

With such a strong pump, it would be best to use an overflow kit that has the skimming overflow teeth at the top (as they use for drilled tanks). Put your intake in the bottom of the overflow and put the pump at a level lower than the intake outside the tank. This will help in priming the pump when starting after power failures. Return the line at several points and levels within your tank according to your needs. Use reinforced flexible tubing to get to the tough spots and to cut down of pressure losses due to multiple bends. Use the pvc with holes drilled in it to make the final discharge manifolds. You can use a router to make a slotted manifold if you should desire. Talk to me, I have a lot of alternatives for you that I have made in the past for special conditions.

[ShirleyM]

Hi Tom and all,
First of all, thanks for your advice and help with this.

I've been advised that if I increase the water movement and circulation in the reef, then nitrates and algae issues will cease to be a problem. It looks like the algae is not hair algae, afterall, but Maiden's Hair Caluerpa. Nitrates on the normal test are about 10-25, lower than I thought (thye've come down) and when Troy did the other test, same kit, where you divide by 10, they were only 1.5-2.5. Either way, they were pale pink, but not "whitish-pink".

I currently have one (1200gph straight line) GenXMak 4 pumping 52" straight up and then into the tank. It is divided three ways: 2 for the built-in overflow uptakes, and one to the top and then down a pvc to the top of the SB. The pvc is capped at the end and has holes punched ever couple inches on the way down.

2 Maxijet 1200's: 1 at each end, toward the front, shooting across the front about 2" below the surface.

1 Maxi 1200 in the back corner at the bottom that is connected to pvc running the length of the back along the top of the SB and endcapped w/holes facing forward.

With this, I was advised that I needed more flow, and to make the return have only 2 splits to the corners, eliminate the 3rd split, and instead, make a closed loop with the extra GenX Mak4 pump we have. The suggestions was to pull the water from the lower back of the tank, then send it back thru about 2 or 3 outlets across the top of the tank, making a forward to back circulation.

There isn't room for an overflow box in the back, as the rock is stacked against the back and all the way to the top. Our 6-line wrasse would probably end up in there (he's gone over the overflow once, but the way it's set up (durso caps) he just swam around in the column 'til we found him) and snails, etc would go in there, and I'm afraid they'd plug the thing up, plus it wouldn't be pulling from the bottom.

If we set up a pvc bar with holes too small for fish and snails, a LOT of holes, then maybe that would work across teh bottom? We do have a router with a bunch of different tips.

Thanks!
Shirley