Please Help!!

dankoos

dankoos

Member
I am ready to start my 90 gallon FOWLR build after years of research and reading. I thought I had decided on a 700gph overflow from glass-holes..and that would be it. (and I have already purchased a used 700gph pump) I just want flow through my sump w/ fuge...will use powerheads for additional flow inside tank. However, someone suggested I drill a second hole as an "emergency backup" in case my one hole gets clogged. With the glass-holes setup, is that a real possibility? (this person used the example of a tang or other larger fish getting into the overflow somehow and clogging up the bulkhead or pipe). Couldn't I put a screen over the overflow box to prevent something like that? It already has the "teeth". I want to drill as little as possible as I am already afraid I am gonna crack my new 90 gal tank...but I DON'T want a hang on back siphon overflow. I am a pretty good do-it-yourselfer, so I have faith I can drill the tank, but one hole is enough for me..plan on having the return go over the back of the tank. This is an in-wall setup, so that won't be seen anyway. I think the 1500 model from glass holes is too much flow for me...i could always drill a second hole w/ upside down elbow slightly higher than the overflow...should I do that?????
Please help!!!! There are way too many ideas/possiblities in this hobby...that can be good and bad!!!
 
jackri

jackri

Active Member
I personally wouldn't drill another hole. Is it possible a dead fish could clog the hole enough to stop flow going out completely?
 
jackri

jackri

Active Member
I know what I'd do.. and that's not drill another hole. Do you have teeth now for an overflow or just a hole water drains out of? I didn't completely understand your drain but I'm tired and trying to study boring stuff so that's not helping either.
 
bulldog123

bulldog123

Member
Just a week ago I had to net the clown out of the overflow. Up over the teeth and into the overflow. But he didnt die.
 
J

jstdv8

Guest
The fish by himself in the overflow wouldnt do anything to the water level. he would have had to get sucked into the siphon tube and plug it up to make the water rise.
If you lose siphon on the overflow you will have a big mess on your hands.
If you can put an automatic shut off on the water level of your sump in the return pump chamber so that if the overflow stops working the water level will go down. put the shut off at a safe point in your sump. this will also save your pump from burning out in case of an accident.
If you left enough room in the sump in case your power goes out for the overflow to take on all the water from the tank until the overflow is out fo the water then the overflow getting losing siphon is the only other casue for concern.
 
dankoos

dankoos

Member
The glass-holes overflows do not require a siphon. They have a hole drilled in the tank. The only way for them to overflow is if a fish or some other object completely blocks the bulkhead or pipe. Water flows through the teeth, into the box and out the back of the box through the bulkhead in the back of the tank.
I am now thinking of getting their model that has two holes..its only an extra $20 but does require me to drill a second hole.
 
xcali1985

xcali1985

Active Member
The best thing about building a custom sump is that you can account for everything, my return pump chamber, which would be the only thing pumped back into the tank if siphon was lost, does not hold enough water to overflow the entire tank. :)
Thats what you have to take into account is does your return pump chamber hold enough water to overflow your DT. The other chambers will remain full.
 
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