Overflow Concern

[JMRegan]

I recently set up my first RR system. It is a 72 bow with a 20g long underneath. The 20L is baffled into three chambers. I have been turning off my mag 9.5(return pump) to simulate a power outage and it seems no matter how I move the water intake in my Overflow box, the 20L still overflows. I have tried keeping minimum amounts of water in the 20L to do it but still it did not help. I know my baffles are a little to high and return chamber is probably to small and that is keeping to much water in the 20L. I was hoping to find another solution other then building a new sump.

Can anyone help me out on this one. It would be very appreciated.

 

[mnavick]

pics?

 

[JayM]

Please post a picture of the durso (drain) height in the overflow, and also the sump. 20 gallons of sump should be OK if it is dialed in correctly

 

[jayman10134]

how does the height of the drain affect the amount of water that goes down it? like you said in your original post the problem is your baffles and mostly your small return pump chamber.

 

[mnavick]

how does the height of the drain affect the amount of water that goes down it? like you said in your original post the problem is your baffles and mostly your small return pump chamber.

If there overflow has mid and bottom holes and the durso drain is low water will keep draining into the sump. If the durso is just below the top overflow holes that's where it will stop draining hence less water into sump.

 

[JayM]

how does the height of the drain affect the amount of water that goes down it? like you said in your original post the problem is your baffles and mostly your small return pump chamber.

The stock overflow on an AGA tank, with a stock AGA overflow kit has an andjustable height durso on the drain.

If the adjustable durso is set too low, when the return is shut down, more of the water in the overflow container will go into the sump. I'm trying to make sure that whatever level is set will make the minimum difference to the sump height.

 

[JohnK]

Is water siphioning back through the return?

Messing with the duroso will only affect how far down the water drains in the overflow box. The duroso will have no effect on how low the water level drains in the rest of the tank.

The AGA type overflows with the slits part way down actually have a double wall that extends to just below the height of the upper slits. Because of this, it will only drain as low as the top of that inner wall. If the water is draining lower than that inner wall, it's because water is siphioning down the return.

 

[jayman10134]

the only change in water level results from the water in the tank. not the overflow itself. therefore making its water height negligible. take the regular standing height of the water in the overflow and call that zero. after you shut down the return pump and let it completely drain. the only change will be in the tank itself, not in the overflow. making the height of the drain negligible. is this correct? as for the middle and top overflow slits, they all go to the top before entering the overflow compartment.

 

[wrassefan]

without a pic....my guess is the return pipe is set so low that the water is siphoning in a backflow...need to break that siphon by either raising the return nozzle higher to suck air at a certain point or a backflow preventer (which many don't work well or will need maintenance regularly)

 

[JMRegan]

Sorry I just got home from work. I will try to post some pics tonight. The return has a drilled hole in it to stop siphon. I am using the overflow pieces JAYM used when he had the tank.

 

[JohnK]

How much (or little) extra volume do you have in the sump?

Also, double check the position of the siphion break hole. How much water drains before the siphion breaks? If the water is dropping lower than that inner wall of the overflow box, you may need to fiddle with the siphion break (for example if it's drilled in loc line, you may be able to rotate the locline 45 degrees or so so that the hole is sitting higher and the siphion breaks sooner).

If the water does not drain lower than the inner wall of the overflow, you may simply need more room in the sump.

 

[JayM]

Sorry I just got home from work. I will try to post some pics tonight. The return has a drilled hole in it to stop siphon. I am using the overflow pieces JAYM used when he had the tank.

I know, it was a standard AGA overflow kit, standard adjustable durso drain and dual output locline return

My sump was less than 20g before I tied that tank into my basement system, and I never had a flood there caused by THAT, so something is wrong here.....

 

[delta]

Even with a hole drilled in the return, you shouldn't leave the return too low in the water . the overflow should control your tank water level not your return siphoning back to the sump.

raise the return out put up to the top of the water when the tank is running and then try it. From there you can adjust down

also make sure you calculate how much room you need in the sump for the size of the tank drain off. http://reefcentral.com/index.php/sump-volume