Noob Plumbing Help

[Miller Aquatic]

I’ve had quite a few saltwater tanks but never one with a sump. So I got a 135 gallon tank which has 2 holes I was thinking one return and one overflow. Each hole is 2” and the overflow box I have is 800gph Fiji box(I think).The overflow box has two 1.5” inch bulkheads herbie style drains. These two holes are on the side of the tank and was wondering the best way getting water to and from the sump with the least head pressure?
I’m gonna convert my 60g breeder into a sump soon. (Fowlr system) also I’m in the middle of scraping off old paint.
Would this setup work?

 

[Miller Aquatic]

so I’m assuming when I start plumbing the return should be 1.5” pvc and the overflow should be two 1” pvc? Also will the 800 gph return pump be ok? I’m planning on having large power heads for in tank flow.

 

[MarineandReef Jaron]

The two holes are likely both for an overflow box. The larger boxes use 2 1.5in bulkheads. Link to the larger overflow box below. For the return, I would recommend going over the back or drilling a new hole if one is not already drilled.

https://www.marineandreef.com/Fiji_Cube_1200_GPH_External_Overflow_Box_p/rfi62982.htm

 

[Miller Aquatic]

I thought that 5x turnover overflow would be sufficient through the sump

 

[Miller Aquatic]

Also looking at the larger overflows it looks way too close for those for hole sizes.

 

[MarineandReef Jaron]

Since this is a used tank I do not know for sure what the original owner did. However, Nobody who knew what they were doing would use a 1.5in bulkhead as a return. It is possible this was a double drain setup without an overflow box.

 

[KrisReef]

I thought that 5x turnover overflow would be sufficient through the sump

Agree that these holes are not for an overflow, one is lower than the other.

I think I would find an adjustable overflow box and get two and use one for the main and the other for the emergency backup for the main.

I would route the return(s?) over the top and the Cadillac return would through a Seaswirl.

Not sure about the hole sizes for this setup (drain or return) but that’s another thing.

 

[Miller Aquatic]

Agree that these holes are not for an overflow, one is lower than the other.

I think I would find an adjustable overflow box and get two and use one for the main and the other for the emergency backup for the main.

I would route the return(s?) over the top and the Cadillac return would through a Seaswirl.

Not sure about the hole sizes for this setup (drain or return) but that’s another thing.

Could I just ditch the overflow box idea and just put both holes 1.5inch drain with a 90 and a strainer? Then just put the return over the top

 

[KrisReef]

Could I just ditch the overflow box idea and just put both holes 1.5inch drain with a 90 and a strainer? Then just put the return over the top

Yes, a lot of fish stores are plumbed that way. The reason why people add the over flow box is because it is easier to get the tank level filled closer to the top. The holes in your tank are pretty low inside the tank so a drain there would not allow the tank to fill up much further than that.
If you put an overflow box or even a 90 with a pipe to raise the intake then it would be easier to get the tank “full” with a reasonable pump flow from the return section. Yes, the return over the tank rim would allow you to not drill another hole.

 

[Miller Aquatic]

Yes, a lot of fish stores are plumbed that way. The reason why people add the over flow box is because it is easier to get the tank level filled closer to the top. The holes in your tank are pretty low inside the tank so a drain there would not allow the tank to fill up much further than that.
If you put an overflow box or even a 90 with a pipe to raise the intake then it would be easier to get the tank “full” with a reasonable pump flow from the return section. Yes, the return over the tank rim would allow you to not drill another hole.

So if I put the overflow box in the one hole and a 90 with a pipe in the other how much drainage you are we talking now? How many gph would I need for a pump? I wouldn’t have the hole with the 90 inch elbow fully under probably half

 

[KrisReef]

So if I put the overflow box in the one hole and a 90 with a pipe in the other how much drainage you are we talking now? How many gph would I need for a pump? I wouldn’t have the hole with the 90 inch elbow fully under probably half

The way to find drainage rates is to look by pipe size ( inch diameter) on plumbing sites, gravity drain flow max. There are tables that have the information.

Returns can usually be smaller diameter but just know that pipe diameter size is the key limiting factor for the answer. Look at a couple of those tables and you’ll find the answer for your situation.

 

[KrisReef]

The way to find drainage rates is to look by pipe size ( inch diameter) on plumbing sites, gravity drain flow max. There are tables that have the information.

Returns can usually be smaller diameter but just know that pipe diameter size is the key limiting factor for the answer. Look at a couple of those tables and you’ll find the answer for your situation.

Also, larger drainage pipes are less likely to clog up with a snail and provide more protection for those situations.