All glass pre-drilled overflows

jester

jester

Member
Anybody know the flow rates for the All glass brand overflows? No info on thier web site.
It comes with the holes drilled 1 1/2 & 1 3/4 holes. What kind of rate can I get out of these, and which one is the return( i don't want to buy thier kit, unless anybody thinks it's decent and QUIET)
 
jester

jester

Member
So A mag 7 would be a good choice. Unless I have a lot of bends, then the mag 9. It is pretty much be a straight drop into sump, but may wander a little to refugium or something on the way back.
 
rockface

rockface

Member
This is a great question. I'm in the process of looking into the same thing. If 600 gph is the max, then would having a bigger hole drilled increase that? Would two over flows double it to 1200 gph. I've talked to several tank makers that say they can drill up to four overflows to flow well over 2500 gph. My understanding from talking to my lfs is allglass will only drill the hole size they want to drill. If that's the case it sounds 600gph is the max.
 
rockface

rockface

Member
so would two overflows on their 240 make that about 1200-1400 gph, if you used two mag 7 pumps?Is it more based off of return pump size, or overflow rate? I would think you would want to go big on your return pump, and use a ball valve to be the safest, correct? That way you could get the max. flow rates out of your returns.
 
reeflooker

reeflooker

Member
One thing to consider... you could use the return hole as a drain. This will increase the flow capacity. You could plumb a return line from the sump to the aquarium using a spray bar or a multi port bulkhead.
Good luck.
 
sweetjesus

sweetjesus

Member
OK, now I have to butt in here and type from personal experience. I have an All glass 90 gallon reef ready with one corner overflow.
I am running a mag 24 pump as a return from the sump.
I emailed all glass and they said the overflow maxes out at 1000 gallons/hour.
What i had to do, is enlarge the overflow slots. While I will admit a mag 24 is tooo much power, man does it create some flow. I am going to be changing stands next week and mod the overflow some more with a dremel and perhaps use the 3/4" line as a drain as well. I am not sure yet. But to reduce the flow of the mag 24, I also power a venturi skimmer. So in all honesty I would guess the overflow is running about 1500 gph with the enlarged slots. and a 1 1/4" drain line.
To further answer your questions, the largest hole is always the drain line and the smallest hole is always the return line.
Hope that helps.
Patrick
 
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