Questions about building overflows and drilling a tank?

[Palster]

I have finally found homes for all of the Cichlids in my 135 gallon tank and am now ready to drain it and get it drilled and build overflow(s). The tank will be used initially as a FOWLR but I want to have the option of having enough flow if I decide to turn it into a reef tank later on. I have been doing lots of research on building overflow boxes and return lines but I still have lots of questions as I haven’t been able to find all of the answers I am looking for through web searches. What I am wondering is should I go with two overflows (1 in each corner) in a 135 gallon tank (72”L X 18”W X 24”H) or would one be enough. Also if I go with two overflows should I run a return line bulk head up through both overflows or would one be enough. I wan to keep the return line inside the tank and not have to run it up the back of the tank on the outside. Another thing I am not 100% sure about is whether or not it is ok to drill the bottom glass (is it tempered glass?) on a 135 gallon Sea Star Aquarium (the ones built in Victoria). Finally I am curious as to what size to build the overflow box or boxes (if I go with two) in the tank (the overflow box in my 90 gallon is approx. 7 ½” by 5 ½”) which gives me enough room for a Durso Standpipe and the return line.

[SeaHorse_Fanatic]

On my 65g, I built a 8" tall by 6" wide by 4" deep. I have it drilled for a 1.5" outflow & I have my 3/4" return comes back the other side.

If I was to do it for a 6' tank, I would probably do the same for each corner, but I would have the overflow set maybe 6" from the side, so you don't see the "ugly" inside of the overflow & would have water entering from 3 sides of each overflow.

Just my experience & thoughts. There are other reefers with much more experience with overflows, so hopefully they'll chime in with their ideas too.

Have fun.

Anthony

[Palster]

So after doing a little more research on this I have decided that I am going to go with an 8" by 6" internal corner overflow but I am still not sure if it will be necessary to have 2 overflows to provide enough flow for a 135 gallon tank. Also I have been told that the bottom of the Sea Star tanks is drillable (non tempered glass). Can anyone confirm these ideas?

[Richy44]

Sorry to but in here but may I ask why you decided on the internal overflows versus external? I am getting ready to build my tank and have decided on external. Just wanted to know what your reason was to go internal..

Thanks

Rich.......

[Palster]

Originally Posted by Richy44

Sorry to but in here but may I ask why you decided on the internal overflows versus external? I am getting ready to build my tank and have decided on external. Just wanted to know what your reason was to go internal..

Thanks

Rich.......

I have been tossing around the idea of going with external overflows myself but after doing some research on the subject I have come up with two conclusions. External overflows can possibly fail and dump water on to the floor. Also they do not move as much gallonage as internal overflows which means you cannot run a large return pump without having to limit its flow or you risk overflowing the tank. The other reason I am not as fond of external overflows is because I want to place the tank as close to the wall as possible for aesthetic reasons. These are only the conclusion that I have come up with and I certainly do not consider myself an expert on the subject or I wouldn't have started this post.

[Richy44]

Thanks Palster..I appreciate your comments..

Rich........