My newest tank!

[mcox3]

You have options. You will need to use both holes in the over flow for draining as you mentioned.

You could use the hole outside the box for returns and use check valves. I have check valves on mine. Regardless of what you do, you will need check valves on the returns OR drill holes in them to break a siphon. If the power fail the water in the return lines will back flow creating a siphon.
Yes, check valves could fail, but an airplane could also crash into your house and then you won't have a tank anyway. I know the odds on one are more likely than the other, but still, come on!
Check valves work best when vertical as opposed to horizontal.

You you plug the holes and drill more in the OF box. You will still need check valves or drill holes to break a siphon.

You could plumb it up the back and over. Mine came with an set up like that for more jets. I'll take a picture of it later. I have to go to work.

There are many more options. It's all person preference.

Okay. I'm going to use the two in the OFB as the filter-drain. The two outside the OFB as the water-change-drain w/ball valve.

Final question- Could I drill holes in the top piece of acrylic to run my return pipes through them. Its going in the wall so the only thing you would see is a bulkhead and two 45 degree elbows shooting water in.

 

[Star_Rider]

I bet this may have been a salty tank with a closed loop. those holes in the bottom would be for the closed loop. the overflow for a sum or it could have been incorporated.
you can still use the tank with modifications.

 

[mcox3]

I bet this may have been a salty tank with a closed loop. those holes in the bottom would be for the closed loop. the overflow for a sum or it could have been incorporated.
you can still use the tank with modifications.

it was a salty tank

 

[Alan R]

Okay. I'm going to use the two in the OFB as the filter-drain. The two outside the OFB as the water-change-drain w/ball valve.

Final question- Could I drill holes in the top piece of acrylic to run my return pipes through them. Its going in the wall so the only thing you would see is a bulkhead and two 45 degree elbows shooting water in.

You could. I cut acrylic using a circular saw with a plywood blade. It wasn't hard to manage. Probably be best if you used a hole saw.

 

[catnipgal]

what??

No sharks in a 400 gallon tank? :cry:

 

[mcox3]

No sharks in a 400 gallon tank? :cry:

No no sharks here...

Here are some update pics...

 

[Reddog80p]

Nice. :thumbsup:

 

[Alan R]

Very nice. Glad i could inspire you to use the extra holes for ball valves to do w/c with You'll find it makes w/c a breeze.

 

[mcox3]

Very nice. Glad i could inspire you to use the extra holes for ball valves to do w/c with You'll find it makes w/c a breeze.

Yeah def! But it drains pretty slowly...

better than syphoning water in to a 5g bucket tho! thats for sure!

 

[Alan R]

Yeah def! But it drains pretty slowly...

better than syphoning water in to a 5g bucket tho! thats for sure!

Yeah, but with this set up you can go watch tv while it drains awhile and just peak in on the progress ocasionally without having to worry about the siphon hose falling in the floor :lol2:

BTW- That 400 gallons would make a killer Tetra tank. :grinyes: J/k. Kinda.