Not your average drilling question.

[sublime-1]

So,

I got this 90 DAS. I ripped out the internal DAS filter box and scraped off all the silicone.

Then I attached my hang-on overflow, filled it up and moved over all the rock, sand and livestock to it. (it was a running tank when i bought it.)

Anyway, now I have decided I want to drill it, because the overflow is

1.) too loud
2.) a detritus trap and already growing green algae
3.) pushing the tank out from the wall about 8"
4.) generally prone to failure, leaks and overflowing. (yes, I know it's an overflow and thus, prone to overflowing)

Anyway, I don't want to drill the bottom of the tank and put standpipes in because it would require me to break the whole tank down again and possibly force it to cycle.

What I'd like to do is drill the back left corner for 2 x 2" overflows and drill the back right for 2 x 2" inflows.

I was thinking I would plumb the drains with PVC, and plumb the inflows with clear tubing for maintenance. I may also drill 2 x 1-1/2" holes for a closed loop.

Has anyone ever seen, or drilled a tank on the back glass as opposed to the bottom ?


How do the back glass overflows generally work ?

Brad

[8BALL_99]

If you just do a seach most all tanks get drilled in the back wall.. Almost Every tank comes with a Tempered bottem so you can't drill the bottem anyway.. The Factory drills the bottems and then tempers them thats one of the reasons they charge more for RR tanks. Also its not a Great idea to drill the tank without taking it down.. You can do it, I've even done it once.. But its not a good idea and if the back wall were to crack during it would be a Major problem.. A 90 is pretty easy to take down.. IMO its not worth the risk.HTH

Will

[Siffy]

Do a search either on here or google or marine depot forums for "calfo style overflow".

[kgross]

Lots and lots of people drill the back or sides of there tanks for overflows. What you want to figure out though is how much flow you are going to have going over the overflow to see how many drains and what size. A 1 inch hole in the back of the tank will not drain as much water as a 1 inch hole in the bottom of the tank.

One thing to rember is that the more holes you drill in the tank, the weaker the glass is. Personally I would suggest doing your returns up over the top, and for the closed loop you could do the whole thing up over the top. I have built quite a few tanks that have the closed loop intake go over the top of the tank and then down through the bottom of a calfo style overflow box into the tank. Does not take up much room and keeps the glass as solid as possible. I also have a tank setting next to my garage that had closed loop holes, drian and return holes and now has a three piece back glass that does not hold water...

Kim

[hllywd]

Originally posted by 8BALL_99
If you just do a seach most all tanks get drilled in the back wall.. Almost Every tank comes with a Tempered bottem so you can't drill the bottem anyway.. The Factory drills the bottems and then tempers them thats one of the reasons they charge more for RR tanks. Also its not a Great idea to drill the tank without taking it down.. You can do it, I've even done it once.. But its not a good idea and if the back wall were to crack during it would be a Major problem.. A 90 is pretty easy to take down.. IMO its not worth the risk.HTH

Will

I disagree about most tanks being drilled in the back and also about most having tempered bottoms. From experience, I drilled the bottom of my 90 and my 125. A lot of people drill the back for CLs but as far as I'm concerned, and again from experience, through the years I've had very few problems with over the back overflows except for the "dead" space behind the tank. I think drilling the back poses the same problem with different plumbing.

I would agree with Kim that you can drill the filled tank, however personally I've never been thrilled with the idea.

Keep in mind that clear tubing will block with algae and cause problems too.

Tim

[TheMcs]

Lots of people drill the back. Huge performance/security as opposed to a HOB overflow.
I've usually built an acrylic overflow box to silicone inside the tank, but an elbow or strainer will work just as well.
A couple holes in the back of a tank won't affect the integrity enough to worry. I would continue to run the return line over the top.
For reference, a 1.5" bulkhead behind an 8" x 4" overflow box easily handles a Mag12.
No idea on what panels are tempered if at all on DAS tanks.

[sublime-1]

Well, thanks for all the responses.

None of the glass is tempered, according to DAS. The bottom has wood underneath it as well. So the simplest option is going to be for me to drill the back.

I don't want to get carried away with it, but I definitely want to create a more secure, and scalable water flow.

I will post more info as I get closer to breaking it down and drilling.

thanks

[TheMcs]

Good deal. I've got a 200 gal DAS in the garage and the bottom has no glass at all, just wood with a plastic tray siliconed in. Really floored us why a 42"x42" 200 gal tank was so light until I could see the bottom. I've also got a 120 DAS that has a glass bottom. Crazy Dutch I guess, too many planning sessions in the Amsterdam coffee shops.

[shookbrad]

I successfully drilled 1 hole in the back of my 90G while it was set up. I also successfully drilled 2 holes in a 55G that was set up. The biggest pain was having to spray water on the glass to keep it cool.
I agree with TheMcs. on the overflow idea. You need a larger surface area for the water to flow over. You should only need a 1" pvc pipe if done that way. My OFB is about 16" long 2" deep and 4" tall. It works great.

[sublime-1]

The oflow box I plan to use is 8" wide by 4" deep by 9" tall.