HOB PVC overflow with no box.

[sjm817]

No Need for a hole at the top and a pump. You just added a potential vacuum leak where there was none before. The CPR needs it because it cant keep bubble clear due to the C Channel design. Just get a decent overflow such as an Amiracle or Lifereef, use it as is out of the box (maybe a standpipe to quiet it) and it works as designed without issue. Lifereef has been selling them for 20 years without a single reported problem. That sure beats 3 seconds!

 

[Gordonious]

U-tube never losses siphon? How is this possible? Try unplugging your return pump, then plugging it back in 5 minutes later...... U-tubes can lose siphon during a power outage.
Also the aqualifter is extra security not a requirement. Tons of people built these with out the aqualifter or anything like it.
I have seen a U-tube with large bubbles trapped in it before after a power blink.

Jon

 

[theop]

U-tube never losses siphon? How is this possible?

Because the U-tube ends are always submerged, even when the return pump goes off.

Try unplugging your return pump, then plugging it back in 5 minutes later......

I do this all the time to feed or clean out the sump. The U-tube stays full of water and does not break siphon.

I have seen a U-tube with large bubbles trapped in it before after a power blink.

Where are the bubbles coming from? Few if any bubbles should be generated from the return of flow from the tank into the internal overflow box.

I am not trying to turn this into an argument, but there are limitations to both designs. A siphon-based device can always fail.

 

[Lee_Bay]

<a href=showthread.php?s=&postid=6505906#post6505906 target=_blank>Originally posted</a> by fareforce
The first one I posted can't get air trapped inside of it.. It has an air excape port in it.

Wouldn't this air escape port also be THE reason it can't hold siphon?

If 90 degree fittings are the reason air gets trapped, couldn't you use two 45 degree fittings and eliminate the problem without adding the air escape port. Unless I am looking at something wrong, this would keep this contraption from losing siphon providing that the 90 degree turns are the air bubble trap.

Any thoughts?

 

[sjm817]

<a href=showthread.php?s=&postid=6512533#post6512533 target=_blank>Originally posted</a> by Gordonious
U-tube never losses siphon? How is this possible?

I already answered that in the last post.

Try unplugging your return pump, then plugging it back in 5 minutes later......

Like I already posted. I do it every single day during feeding. Its off for ~ 10 min. I've had it off for 3 days when setting up a new sump.

U-tubes can lose siphon during a power outage.

Not true. Maybe one that is a poor design or not setup right, but by design, they do not lose siphon.

Also the aqualifter is extra security not a requirement. Tons of people built these with out the aqualifter or anything like it.

Nope. Not needed. It just adds a vacuum leak. Bad idea.

I'm not saying a DIY PVC overflow is a bad idea. Just do it for the right reasons. If you want to do it because you think that a traditional U Tube overflow doesn't work, you need to do some more research to understand how they work. You seem to have got some bad information from somewhere.

 

[Abysswater]

I think the word that everyone is trying to point out is "water buoyancy" If the outer box and inner skim box are at same level there will be no break in a u-tube design. If design is right. Now if the outer box was lower than inner box there is a breaking point
of level drop, and air can get in if enough force is applied. But many overflow boxes are design with u-tubes will be design like this. Level or having a bigger volume of water in outer box to control static pressure. It's kind of like putting a cup underwater and turning it upside down and holding it above the surface. Well the water is still inside of cup, untill air is applied inside. And if air get trapped in side of a u-tube design you do not have a vary strong flow to begin with.

 

[Gordonious]

I didn't mean to be rude to anyone and hope no one was offended.

"if air get trapped in side of a u-tube design you do not have a vary strong flow to begin with."

Could this be another reason why the PVC would be better for me? Not only is there not enough room behind my tank, but my tank is also a small 20g tank, a large number of gallons per hour, would flush out the animals in the tank.

Jon

 

[sjm817]

One concern I would have in a PVC overflow is the use of solid PVC. You want the siphon tube part to be transparent so you can see if you have air accumulation issues.

You dont need a ton of flow to keep a U Tube clear of bubble accumulation. A Mag3 is plenty for that and would be a good size pump for a 20G.

Another advantage of a traditional overflow is the skimmer box weir skims the surface and keeps snails and such out.

How big of a sump will you have?

 

[Gordonious]

All said and done there will be ~90 gallons in my system. I have two display tanks (20g long) back to back. There will be two sumps side by side (20g tall). And in the middle, height wise, there will be one or two 5 gallon tanks.
I've been asked before why didn't I just buy a large tank and make a sump for it. The reason I have done it the way I have is because I could only have a 20gallon and a small sump when I lived at my parents, upstairs. When building the stand for it, the dimensions of the stand was so close to being able to fit two 20longs on top I might as well have built it that way so I could in the future. I now live in my own place and am starting to put things together. <BR>
<BR>
I'm considering taking the tank that is on the left, opposite side from my desk, and drilling it. I have a French Angle in it at the moment that I could move to the other tank, while I attach the PVC fitting with aquarium glue. After doing this I would run two U-tubes from the tank on the right to the tank that would then be drilled. Doing this and leaving the PVC overflow on the right tank I think would be pretty safe and effective.

The original stand: <BR>
<img src="http://www.gordonious.com/H2O/The%20future/tankstand2s.jpg">
<img src="http://www.gordonious.com/H2O/The%20future/tankstand1s.jpg"><BR>
<BR>
Current set up:<BR>
<img src="http://www.gordonious.com/H2O/The%20future/HPIM3224csSideoftanks.JPG">