Daplatapus's upgrade

[daplatapus]

The tank originally comes with the 2 internal overflows. The drains are 1" durso's and 3/4" returns. I want to go with the herbie design though.
On my existing system I was stuck with existing holes and am actually running a 1 1/4" full siphon but at the bulkhead it reduces down to 3/4". I had originally run the 3/4" all the way but it couldn't keep up to the flow demand. That's when I used bushings to increase it to 1 1/4" on both sides of the bulkhead and it ended up being a bit overkill. My gate valve is probably only about 25% open.
So on this tank I'm thinking of using the 3/4" holes for my siphon but increased to 1" on either side of the bulkhead and use the 1" holes for my safety drains increased to either 1 1/4" or 1 1/2".
I really don't like the over the rim returns on my existing tank so I'm thinking of drilling 3 or 4 - 3/4" returns in the back of the tank. I did this with my cube and really like the results - it looks nice and clean. I've been able to drill the MIP-Locline adapter and have no issues with back siphoning when the power goes out. But it is only a 20 gallon cube, not a whole lot of pressure. If I drill the 3/4" holes as high as I can get them (which is roughly 1/2" down from the black plastic rim on the top of the tank) I'll be about 2 1/2" down from the top of the glass to the edge of the hole. And I was originally thinking 4 holes, 1 on either side of both overflow boxes. But I suppose I could get away with only 2 holes on the right side of the left overflow and the left side of the right overflow. The factory returns come with a splitter on them so in essence there is 4 returns anyway. Anybody see any issues with drilling that many holes? Or should I just go with the 2?

[daplatapus]

The other question I had (it just came back to me) is for those running dual siphon's. Is it hard to balance? Should I be tying them together and controlling with one gate valve? I know if I do it that way all the piping has to be exactly the same length, but it seems better to have redundancy with 2 separate drains. Just not sure how hard it will be to balance. What think you?

[daplatapus]

Any thoughts as to structural integrity of drilling 2 - 3/4" holes on the back pane 2 1/2" down from the rim?

[lockrookie]

drill slowly and carefully very little pressure and go with 4 return holes thi way you can adjust flow to dead areas your powerheads arent covering. try to design your return manifold insuch a way that yuo can have a syphon break to reuduce amount of back flow to sumpinpowerr failure

[Bblinks]

I would use the still use the larger hole for the main overflow and the smaller return hole for emergency. Depending on what you want keep, you can always dial it back if it's too much. This way you can fine tune it once it's all set.

As for the 2 in 1, I think you are better off doing a dual using a gate valve for better control.

[apexifd]

I will just use few pvc 90 and build that return, over the rim of the tank, and back into the water. and drill a small hole on the pvc at water line which will act as your siphon break.

way less work than drilling holes on the back pane and have to worry about too much water drain into the sump during power outage.

[dee105]

Wowza, that's a big tank, I NEED to come see it in person!