drilled tank

[gsl86]

Hi all I'm hopeful some one can answer a question for me I bought a 100 gallon glass tank recently to upgrade from a 55 and it has 8 holes drilled in the bottom in a line down the center of the tank i originally thought they were for a sump but after scouring the Internet for a similar setup I'm at a loss the quantity and location just don't make sense to me so if some one could explain and maybe share a link I would greatly appreciate it

Thanks

 

[PB_Smith]

It was most likely set up with an under gravel filter and probably all but 1-2 of those are drain holes and the other would have been the return(s) usually the end holes were returns.
Saw and built that type of set-up lots of times way back before sumps entered the scene and UG filters were the predominant type used.

 

[Andy Sager]

Another possibility is that they were custom holes for drain lines down to a sump and/or returns up through a decoration. Either way, they are there and you can use them to your advantage. Get through hole fittings for the hole size and use PVC standpipes. Have them drain into a sump ( any sump that can handle the volume of water you need to need to have in the system) or use some as a return and just use decorations to hide them. Having them already drilled opens up a lot of possibilities for you. That's a gift you may not realize just yet.

 

[gsl86]

Thanks for replying so quickly do you know of a site with info on that sort of under gravel filter and what kind of stand pipe would work best with out an overflow box I'm assuming that's what you were suggesting thanks again

 

[Andy Sager]

I use PVC as the standpipes but as for what size, it's going to depend on the size of the holes and what size fitting you can get in there. The principles are going to be the same as a wet/dry filter so you can look up that setup online or ask in a store how to set them up. As for the return, you'll need to plumb the pipe(s) so that the water returns at top water level and you'll need strainers for the tubes that drain water down to the sump. So you don't want to get pipe size where you can't get these things.