Overflow?

[DN328]

Millerkid,

Overflows do have something to do with pumps tho you can't use a 1000 gph pump with 1 x 1.5 drain right? You have to keep in mind the ability of your overflow

I agree with your comment on dependencies between the overflow and return pump. But I didn't get the 1000gph to 1.5" PVC example. Not debating just looking to understand with some clarity. Thanks.

 

[millerkid519]

Ok that was a bad example. 1000gph for a 1.5 inch is actually decent setup but it is at the limit for me personally for gravity ovreflow. Now if I would have said 1000gph threw a 1 inch drain that would have probably made my point a little more clear of what I ment

 

[adamsfishes]

I have a single 1.5" drain pipe for my overflow, and it can handle 1200gph easily, but I wouldn't want to go much higher than that. The size and design of the overflow can potentially limit the flow rate to be slower than what the drain could handle as well.

 

[DN328]

That's true about the overflow being the bottleneck. I have an internal overflow (drilled tank with Herbie style, but with third dry e-drain) where I had to make medications to the weir as my 1" could handle much more.

Dumb question, when folks talk about gravity fed are we talking about gravity fed drains with a full siphon? I wanted to the drains like a BA, but also need room to conceal my return plumbing with check valve and T to split and all. I actually think my 1" primary can take on much more than it can - even with my weir modifications. I know math doesn't lie, but I feel my 1" drain is sufficient for my 300gallons.

OP, sorry to hijack, but my questions are somewhat relevant to your question at hand too.

 

[adamsfishes]

I know math doesn't lie, but I feel my 1" drain is sufficient for my 300gallons.

I'd be afraid. Maybe it can handle it under ideal conditions, but what if the drain gets a partial blockage? I wouldn't want to live on that knife's edge.

I'm pumping about 800-900 gph through my 1.5, which gives me a lot of room for error. I roughly estimate it could take 1800 gph but I wouldn't want to run anywhere near that level. On a 300, I think I would probably do 2x1.5.

 

[DN328]

I'd be afraid. Maybe it can handle it under ideal conditions, but what if the drain gets a partial blockage? I wouldn't want to live on that knife's edge.

I'm pumping about 800-900 gph through my 1.5, which gives me a lot of room for error. I roughly estimate it could take 1800 gph but I wouldn't want to run anywhere near that level. On a 300, I think I would probably do 2x1.5.

If the 1" primary full siphon drain clogs, my second 1" drain will cover. If the two cannot keep up, my third dry 1" will be used. I think I'm covered with 3 drain pipes. You may have missed that in my post? Or did you have a different point? Thanks.

 

[DN328]

Forgot to add, yes, I agree with about bigger size drain too. I chose to settle on what I have to fit everything on my internal overflow. My overflow is roughly 30"L x 6"W x 28" H, and 1.5" pipes would be too big with all return plumbing and a dry standby. I didn't want pipes exposed on my peninsula tank.

 

[millerkid519]

With a gravity drain it is not full syphon it is a air/water mixture like a durso or a stand pipe.

 

[duanes]

Siphon doesn't really have relevance unless using a siphon overflow box. Drilled tanks do not necessarily use siphons, water is pumped up to the tank if the tank is drilled water overflows down the pipe, and there is no siphon involved.
I drill tanks about 5" from the top, and use an upturned PVC elbow, in this way, as water is pimped in, once it fills to the top of the elbow it cascades over the top.

either PVC with cut weirs, above, or none cut, below

Overflows can, and do get plugged easily if plants are involved, or can be plugged with a dead fish etc, using too small a drain can easily end is water on the floor
below is a 1.5" PVC drain

I often let gravity take water from one tank into another, before going to the sump, eg
There is really not a rule about sumps size, I often use larger tanks for sumps than a main one. For an outside 55 gal tank, I used a 1500 gal pond as a sump, to help maintain cooler water in the tank

 

[duanes]

Siphon doesn't really have relevance unless using a siphon overflow box. Drilled tanks do not necessarily use siphons, water is pumped up to the tank if the tank is drilled water overflows down the pipe, and there is no siphon involved.
I drill tanks about 5" from the top, and use an upturned PVC elbow, in this way, as water is pimped in, once it fills to the top of the elbow it cascades over the top.

either PVC with cut weirs, above, or none cut, below

Overflows can, and do get plugged easily if plants are involved, or can be plugged with a dead fish etc, using too small a drain can easily end is water on the floor
below is a 1.5" PVC drain

I often let gravity take water from one tank into another, before going to the sump, eg
There is really not a rule about sumps size, I often use larger tanks for sumps than a main one. For an outside 55 gal tank, I used a 1500 gal pond as a sump, to help maintain cooler water in the tank