Stupid overflow....

[Safir]

I guess it's really "stupid me"

I picked up an overflow on sale, under the advice of the LFS owner that it was a good size for my tank - I took their word for it and didn't think to ask what the flow rate was through it - single u-tube, 1" bukhead, looked good enough to me.

Looks like it flows about 300GPH - i try to pump much more through it and the water level begins ocillating, gulping air on the "down" portion, makign a lot of noise, and slowly raiing the water level in the display - ARGH

I was hoping to get more like 350-450 GPH through it, Soooo. that brings me to my post: anyone local have a 600GPH overflow with a 1" bulkhead that i could pick up cheap?

TIA

 

[mbbuna]

if its not flooding the room then the over flow can handle the GPH. sounds like there's air, food, something, blocking the flow.

 

[Safir]

if i were to leave it alone it would flood the room - the water level in the display continues to raise until it hits the rim then i slow the flow from the pump (so it won't flood the room) and it comes back down.

BUT - i will pull the return line (flex PVC) and check it just in case.

 

[MadTownMax]

drill it, you'll never go back to HOB overflows - it's really the only "fail-safe" method of overflows

 

[Safir]

my next tank will be reef ready, believe me, but this is what i've got now, and I can't afford to drill it, build an internal overflow, etc etc, much less buy a new tank if it breaks (bowfront tanks == $$)

that and my tank has a tempered bottom, so i'd hav to go out the back - bleh

maybe once i have a job again.

 

[MadTownMax]

true - go with a lifereef-style overflow - they're a little less prone to breaking siphon - adding a small hole to the very top of the siphon tube and attaching some airline tubing to either the venturi connection of a powerhead or a cheap vacuum pump will help keep bubbles out of this tube (which can also break siphon)

I know some people have installed durso or stockman standpipes in their HOB overflows - this is also an option which should increase flow capacity.

I'm assuming through all of this that the drain hose is not submerged - this can cause an air bubble to become trapped inside the line and restrict flow...

 

[kaptken]

SAFIR,
I've used the tidepool SOS,(silent overflow skimmer) on my undrilled 75 for about 8 years now. hasn't overflowed yet. it handles about 600 gph. i have been using a mag 7 sump pump, which at the 3 foot head puts about 500 gph into the tank. works great and its one of the least expensive. the removable flat rectangular type syphon tube has a built in slot for a length of air tubing to suck out the bubble. just put the loose end in the outside chamber to keep it full. heres the link to TFP.

http://www.thatpetplace.com/Product...rs/T1/F26JB+0221+0230/EDP/18028/Itemdy00.aspx

I also use their tidepool biowheel sump, which doesnt hold enough water in the sump chamber to overflow the tank just in case i broke syphon. its slightly adjustable for water level in the tank. check it out. i wish i had a reef ready. but this syphon has worked just fine. i still have to suck out the bubble every 4 or 5 days. but not a problem.

 

[Safir]

Thanks for the advice - i'd heard mixed reviews on the SOS so i was wary, but it's good to hear a favorable review from someone whos opinion i actually trust

I've ot things running as well as possible for now, once the last of my loc-line fittings arrive I will asses the flow I can get from it and determine what course of action i need to take.

thanks for the input guys.

 

[kaptken]

you're welcome.

but dont forget that an important part of flow calculations is the sump capacity. especially if you are worried about a syphon overflow problem. the trick is to size the total sump volume large enough to handle the drain back from the tank in a power outage or pump shutdown . but keep the operating level where if the overflow shut down, draining the sump with the pump wont overflow the tank. its an important calculation people seem to forget. but soon learn when there is a problem. bigger sumps are not always better or safer.

and also any other secondary syphon paths like air tubing or other hose will also drain the tank to their lowest open end. so putting a sump pump discharge line well below the tank surface will drain the tank to that level and overflow the sump in a power outage. to prevent that you need a little 1/8 inch hole drilled in the back side of the tank supply header or spray bar just below the tank water surface, where it wont spray out of the tank, of course, to be the vacuum syphon breaker.

 

[Safir]

all good points ken -

both of my return lines have siphon breaks right at the normal operating water level in the display, and to determine total water volume I filled my sump 1/2 way, ran the pump until the water level in the display stabilized at norml operating level, then shut off power to the system - allowing all the pumps to stop, the emergency air pump to begin pumping air, and as much water as might to drain back to the sump. I then topped off the sump to the bottom of the black trim (just to give a little lee-way) and the stem was started back up. i marked the water level in the return section so i had a reference for top-off.

the corals are going in a nano that is cycling ATM along with my pistol shrimp:

http://www.reefcentral.com/forums/showthread.php?s=&threadid=867257

 

[kaptken]

sounds like you have it under control, except for an undersized overflow at the moment. nice set up and DIY sump. looks neat and functional.

 

[wds21921]

I've had overflows but not yet had to deal with any bubble build ups in my siphon tube(s), even with bubbles in the tank from say a protein skimmer.
Ken gave me an extra siphon tube but my overflow box wouldn't accomodate two 1" tubes in the initial chamber. I got a 3/4" piece of vinyl tubing to replace the rigid tubing and it's bumped my flow to 600 - 800gph.
One side note is the difference after you've gone to a higher flow rate. The tank seems to adjust to it much better and with better results. If the flow is slowed down any (say removing one of the two overflow tubes) there is a quick growth of cyano and other undesirable side-effects. From what I've seen so far the faster flow/better results theory seems to be true.