diy overflow

[Castro235]

Well, it seems like maybe this undying thread has finally died, but I figured I'd see if by chance anyone with some experience had a word on my overflow.

Just finished setting it all up, as far as my week or so going back and forth through here and every other DIY forum goes I think I have all the math right.


The lower bottom U on the inside of the tank is slightly higher than the bottom U on the outside of the tank, I have the elbow inside of the tank level where I want the water, although I have a question about that.

I also have a hole in the top of the caps at the highest point after the bottom U on the outside of the tank.


My question about the elbow inside of the tank and the water level, I'm sure it's somewhere in the 78 pages, but somehow it's eluded me.

Will the tank drain until the bottom of the elbow's opening, or once there is any air getting into the U will it break the siphon, or does it happen somewhere in between?

Obviously I'll find out when I'm testing, but I'm just curious if anyone happened to know, since this seems like the place with the most experience on DIY PVC overflows.

 

[Castro235]

I apologize for the double post, but if there's an edit button I couldn't find it lol.


I am adding check valved in the topmost U where it hangs on the tank, just took a pic once I fitted everything.

 

[cypher1024]

It looks great! You probably already know this, but you'll need check valves in the top of both U sections that cross over into the tank.

Also, the edit button is only available for a short while after you post, then it disappears.

The lower bottom U on the inside of the tank is slightly higher than the bottom U on the outside of the tank, I have the elbow inside of the tank level where I want the water, although I have a question about that.

My question about the elbow inside of the tank and the water level, I'm sure it's somewhere in the 78 pages, but somehow it's eluded me.
Will the tank drain until the bottom of the elbow's opening, or once there is any air getting into the U will it break the siphon, or does it happen somewhere in between?
Obviously I'll find out when I'm testing, but I'm just curious if anyone happened to know, since this seems like the place with the most experience on DIY PVC overflows.

Ideally ALL of the lower U sections should be at the same height. If you haven't already glued them in place, lengthen both pipes coming from the lower Us to drop them down to the same level as the ones outside the tank.

If you have already glued them, you can test and see if they stay filled, but I suspect that if you have a surge of water, it may end up sucking air in through the Us inside the tank. If this happens, the overflow will stop working.

I also have a hole in the top of the caps at the highest point after the bottom U on the outside of the tank.

Good. Without those holes, you would have created a siphon

 

[Castro235]

It looks great! You probably already know this, but you'll need check valves in the top of both U sections that cross over into the tank.
...
Good. Without those holes, you would have created a siphon

Gar, from all of the looking around it seemed like people were tending to go with the outer plumbing descending farther than the inner plumbing, I would have thought it would be the other way around if anything, but it seemed to go that they were either longer on the outside, or the same height.

Guess it's a good thing I decided against gluing the pipes on the inside of the tank then, so i can just adjust the height of them to match the pipes outside now that I think of it.

Any word on the water level in comparison to the elbow inside of the tank?

Oh, and yes, I already put check valves on both sides, although they're different brands, and I know that won't matter, I found I honestly like the cheap-o walmart check valves better than the Elite brand.

Walmart has a rubber triangle type thing in there, and absolutely does not let air in one direction, but allows it freely in the other, while the Elite is very hard to get air through even in the proper direction.


Also, I have the T in the middle bottom section pointing straight out(so it will be aimed away from the tank instead of down, and I plan on having an elbow attatched to it, aiming a pipe slightly down, and to the side, since my overflow needs to be on the side of my tank instead of underneath.

I don't see that being an issue, but figured why not ask, since everyone seems to ask before they research in this thread lol

 

[Castro235]

Im doing this instead of my physics test. So i need to find some methods that fail and why they fail.

Then find one that works.. N say why it worked.

But first is first. Id like to know how my design is different. It looks the same to me.

also any1 have any designs that failed?

If I can get mine to work i'll right up a full DIY step by step.

As far as I can tell, the only differences in your design from the others are the lack of a check valve, the fact that you have such a long section at the top most U instead of a sharp turn, and that the vent pipe is so long.

I don't think the vent matters as long as its the highest point, so thats fine, you definitely want a check valve, or a tube throughout the piping to go to that point, and I think having that long section will make it too much work for the siphon to properly function, although I really have no idea if that's true or not.


As far as researching it, it's the same concept as a toilet bowl flushing, so you might want to grab some info on that for good descriptions.


Oh, and you have the pipe inside of the tank so low, either the water level will be extremely low because of that, or the siphon might not work going down such a short distance, and then needing to push itself up so high in comparison. again, I'm not 100% sure though.

 

[Castro235]

Well, test one was inconclusive, probably because the silicone on the check valves was worthless lol.

Cleaned it up, and caked on the silicone like crazy, hopefully tomorrow will yield better results.


Also did some poking, and it should have been obvious to me before lol, but for anyone else wondering, the water level in the tank will drop to the lowest part of an elbow that is being used as your overflow input.

 

[Castro235]

Well, after several attempts at using silicone, as much or little as possible, and allowing for up to 24 hours in 75+ degrees for curing, it's just never sealing right for the check valve.

Literally took the check valves out, sucked the air out of the holes, and covered them with a thumb, and they work like champs, so I know that's where the problem is. Decided to just go with the pvc glue for the check valves. Even if I only get a few months before a check valve goes bad, it'll only be 10 dollars or so to replace half of the system anyways, so I'd rather have it working and permanently fixed, than easily replaced but barely working.


Seems like once the glue is cured it should be all functional though.


Thanks to everyone who put all the information I needed into this thread, without you guys, I'd have two emperor 350 HOB filters right now lol.

 

[ph96ers]

does anyone know how to stop the vortex on the water surface, i have a 850 pump with 1.5 abs, flows good but i get that vortex as the water enters the overflow, dont know how to get rid of the vortex.

 

[forgottenx]

You can put a sponge, just make sure its big enough so it doesnt get sucked in. Or use a 90 ...

 

[streetthrowback]

You can put a sponge, just make sure its big enough so it doesnt get sucked in. Or use a 90 ...

i did that to my 2'' pvc cuase i got a water pump thats 1600gph and it slowed down the water flow to the sump, dont know why