overflow for sump and refuge, 2 boxes, bad idea?

ok to make this long drawn out problem story short... with out drilling holes,(not an option right now), so ive been running a refugium with an 800 overflow box and a 700 return pump actually a little slow for it, but id like to set up a sump next to it to skim water and also allow for more overflow backwash capacity., any way after atemping severl stupid things i realize i either need holes or... id like to leave the refuge alone and set up another overflow box say 300gph to the sump w/simmer and then pump back with a 350, my question is and i think i already know the answer but, will one box overpower the other? or one box loose syphin? or could i just run a T off the one existing overflow and a valve to regulate flow to the refuge and the sump and then the 700 and 350 pumps would pump back and i believe they wont overpush the overflow box... any help would be greatly appretiated

 

Tow overflow boxes is near impossible to get balanced. What will end up happening is the intake box on one will be slightly lower than the other and thus get more water. You will also have two pumps running, so the one that's getting more will take in more water than is coming out of that sump and one sump will run dry while the other could possibly overflow. I would just T off the existing overflow to run to both.

 

Running two overflows is no problem at all.

As long as the pump you are using does not naturally exceed the flowrate of the overflow boxes combined or you have a ball valve to control the output of the pump - the boxes will only flow as much water as they are given.

Yes it's true that one will be slightly higher than the other, but typically flow rates out of plumbing does not have to be symmetrical to have an effective system.

Now two pumps - that can be tricky. If both of the pumps are in the same chamber then you should be fine regardless of where they return (obviously has to be somewhere in the system!)

I personally like having two overflow boxes as it gives me valuable options in terms of maintenance and system needs. One overflow box feeds the main 40 BR sump which houses some LR, pads/socks (when needed occsionally), and eventually media reactors. This main sump also has the main return pump (only return pump in my system).

I have another smaller overflow box which feeds just the skimmer and fuge separately (all isolatable by ball valves). The 20Long that the skimmer/fuge is in is divided in two and has two bulkhead returns which flow to the main sump.

In this way, I can turn off the fuge and skimmer from the main system if ever needed. Also in this way, I am using two overflow boxes with one return connecting 3 tanks. I have no issues with the boxes not flowing enough or flow rates not being equal (they are eshopps PF1800 and PF-NANO - the largest and smallest boxes they make). The flow rate does not have to be equal through each overflow box. But you do need to tie the system in with only one return pump for maximum efficiency and simplicity.

 

If they are going to the same place, but if they are going into a separate sump and refugium, you will have problems.

 

Mike I have to disagree with this statement. I reiterate that as long as the SINGLE return pump does not naturally outpace the flow rate capacity of the overflows combined - you will not have any problem if everything is on the same system.

It's two pumps that really is difficult. Two overflows do not have to go DIRECTLY to the same place - as long as all of the water in the whole system is allowed to gravity feed to the same place in the end (like the return chamber of your main sump) - it does not matter how it gets there. And using only one pump eliminates any balancing issues no matter how many overflow boxes you use. You could surround your entire rim of your tank with 20 overflows as long as they all go back to the same spot and are all ran by a single pump, there will be no problems. Again, you will only flow what is given to the overflow box. Not a drop more.

 

Mike - Here is my system which runs off the two overflows like I was saying in my previous post. Not a pretty picture and it's messy in there but it surely works to my satisfaction!

These are two TOTALLY different sized overflow boxes (PF1800 and PF-NANO) they could not be much different in their rated flow capacities. But due to the fact that they will only pass through their u-tubes as much water as the single return pump throws out - it works.

You can see in the picture (in the foreground) the two (2) 1 1/2" flexible PVC lines off of the PF-1800 going directly to the main 40BR sump. The PF-NANO flow is split between the skimmer section and refugium section which then, in turn flow out of the 1" bulkheads back into the main 40BR sump.

Maybe we had different concepts of "two overflow boxes" in our heads - but the design I describe and present to you in picture form works.

 

thanks guys for the imput. i belive that what u r saying about the two overflow boxes being fine but that would lead to me drilling holes either in the sump or fuge and i believe that this will work for me, going to overflow through the original eshopps 800ghp box to a T and go to the fuge with a 700 gph pump back up and a ball valve to the sump with a 350 gph and the two pumps have to travel about 3.5 ft up so i believe that would be about right for the overflow box just have to fine tune the valve on the sump to regulate the pumps in each tank as to not overpump one another. i know its not the best way, but it should suffice for a few months till i move unless a pump dies with is not very likely (knock, knock).