Overflow floods!!! x 3 now !! Help !

[toefutoefutoefu]

When you buy an overflow that is rated for way more flow than what your pump actually pumps up, you will get air bubbles. Plain and simple. if you properly match up your overflow and your return actually pushes the correct amount, then the siphon should last forever.

People tend to buy "for the future" and end up with an overflow that can do 1000+gph, and only have a mag 7 run it. mag7 - head loss, elbows and using 1/2" pvc = ~300gph. typically = siphon loss.

 

[DarG]

This isn't a new concept, it's been working for years and years. Back in the "old" days when filtration was a UG filter and an external hang on back filter, those HOB filters used U siphon tubes to get the water from the tank into the filter box. Anyone remember the old Supreme line of external filters. The siphon tubes didn't lose siphon unless the water level got too low or something knocked a U tube sideways so it came out of the water, or close enough to it. They worked back then , they work now.

A U-tube oveflow that takes into consideration that fact that both ends of the U-tube need to always be submerged under a certian minimal amount of water will NOT fail to keep siphon when there is no water moving through them. As far as build up of air goes while they are actively siphoning water, a certian diameter U-tube needs a certian minimum flow rate to maintain enough velocity through the pipe to keep air bubbles moving in the stream of water instead of building up in the pipe and breaking siphon. As long as the pump meets this minimum flow rate spec, again, the U-Tube will not lose siphon.

A properly designed U-Tube overflow meets the first requirement. When used with a properly sized pump, the U-tubes will not lose siphon and the overflow, as a system, will not fail.

 

[jobob]

My friend has a C type overflow with aqualifter pump keeping the syphon. About once every 3-4months she calls me to come fix it cause it stopped working. Everytime I go over there its because the aqualifter failed. Most of the time its because something got stuck in the aqualifters hoses or the power went out and the aqualifter stopped or reversed. So IME the u-tube with matched pump will not fail during a powerloss the c-type will. Unless you put on a hose with a valve and suck the air out of the c-type, but then isnt just a u-tube. We will have to wait till we see the pics.
GSMguy the u-tube wont fail the C-type will. Propperly set is when the pump is matched to overflow. Although, I have an u-tube overflow between my fuge and sump. I only run maybe 100gph thought my fuge. The u-tube gets filled with air but it never fails. It looks like it will cause theres more air than water, but doesnt. So Im not sure the proper pump matters as much as we think.

 

[GSMguy]

thanks

 

[surfjeepzx]

"My system is this. a 75 gallon with a 20 gallon fuge with a overflow box that runs down into a sump and gets pumped back into the fuge by a pump."

I have a feeling it has something to do with the sump>pump>fuge part. This arrangement is never good if there's not a gravity equalizer somewhere between the sump and fuge.

 

[jobob]

Yea you cant have overflow to sump then pumped to fuge then pumped to main tank. It will never work I tried it, thats why put an overflow box between the sump and fuge.

 

[johngeb]

I didn't get a chance to take pics but here is the layout. I'm not sure what rateing is for the return pump, maybe 300-400.

 

[jobob]

I dont understand ur drawing. The main and fuge are at the same height? Is the 75g the sump, and another 75g for main tank? Or the overflow from the fuge goes into a bulkhead at the bottom of the 75?

 

[johngeb]

Hope this drawing helps

 

[DarG]

OK, looks to me as if you are using a pump to get water into the fuge from the main tank. Then water from the fuge overflows into the sump. The sump pump retruns water to the tank. But the problem is that you are actively pumping water from the tank to the fuge. If the overflow from the fuge to the sump ends up being more GPH than the pump returning water to the tank can handle due to the tank to fuge pump being stronger than the return pump then your sump is going to overflow. If the sump return pump is stronger, it will end up running dry. Both are possible in your setup because you are actively pumping water from the tank to the fuge. Which one occurs depends on which pump is stronger. You can't move water from the tank to the fuge by way of pump and then have this water flow to sump and then expect a second sump return pump to match the output of the first pump.
Water needs to passively overflow with one pump (or more doing the same thing, not different things) ultimately controlling the rate of overflow.

This is Assuming that I understand your drawing.

 

[tkeracer619]

yeah, cannot pump water out of the tank and back in.

Need to pump water in and let it overflow out.


This whole HOB U-tube argument is rediculous. To each person their own cake I guess. I have a properly set up U-Tube overflow, it sucks, they can cause a flood. I have yet to have complete falure but have lost siphon in one of the two tubes. Never again will I go that route. Murphys law.

 

[DarG]

<a href=showthread.php?s=&postid=9954255#post9954255 target=_blank>Originally posted</a> by tkeracer619


This whole HOB U-tube argument is rediculous. To each person their own cake I guess. I have a properly set up U-Tube overflow, it sucks, they can cause a flood. I have yet to have complete falure but have lost siphon in one of the two tubes. Never again will I go that route. Murphys law.

If you lost siphon in one of your U tubes then either your pump isnt strong enough to keep enough water flowing through the tubes to keep clearing the air bubble or the end of the tube was lifted out of the water or close enough out to lose siphon. There are some really weel designed U-tube overflows out there and they will not lose siphon if properly set up with a pump that provides adequate flow unless the U tubes are physically disturbed.

Try a Life Reef overflow if yours isn't trustworthy.

 

[tkeracer619]

My flow is matched with the overflow. I don't doubt the design or the fluid power transfer. I understand these things and that is why Murphy's law will win in this situation.

If it can fail, it will. A better solution is to have a drilled tank. I see a U-Tube overflow as an easy solution to a normal problem, I took the easy way on my first tank and have regretted it since. Taking the time to drill a tank or when you upgrade buying a RR tank will save a potential disaster.

In the year this tank has been set up I have not flooded my house yet with it, though I did come very close one day and will be upgrading to a drilled tank before I run into it again. Besides, drilling a tank takes a $5 bit from ebay and some time. Much cheaper than a U-tube HOB and much much more reliable.

 

[Zach117]

This thread & u guys make me worry that I am going to have 150 gal of water on my floor. I just put in the double box lifereef overflow and I am using an Eheim 1262 as my return. I also have a (peristaltic) or whatever you call it Litermeter for ATO so the water level will always be constant. As long as it does not flood in a power off when the sump fills up I am fine. Right?

 

[DarG]

Zach, you are completely safe. Your life reef is not going to fail and flood your home.

As far as Murphys law goes. Your bulkheads could fail on your drilled tank. You can get salt on one of your plugs and burn your house down. You could crack your tank while drilling it. Your pipe in your built in overflow box could get clogged when a snail makes his way down to the first 90 degree elbow and flood your living room.

Or is Murphys law that selective that it only applies to HOB overflows ...

 

[Zach117]

you forgot about the skimmer overflowing and dumping the entire tank out, but mine is internal so no worry.

 

[toefutoefutoefu]

even if the skimmer dumps the entire tank out, the over flow will not fail either.

if one of your tubes is losing siphon, you overflow is outrunning your return pump too much. You are clearly not calculating the return correctly. Those headloss calculators are pretty correct when they calculate your 900gph pump down to 500gph.

a double tube overflow is probably rated at 1200gph, and you're probably using a 1200 gph pump that drops down to 700 gph when said and done.

 

[sjm817]

<a href=showthread.php?s=&postid=9954255#post9954255 target=_blank>Originally posted</a> by tkeracer619
yeah, cannot pump water out of the tank and back in.

Need to pump water in and let it overflow out.


This whole HOB U-tube argument is rediculous. To each person their own cake I guess. I have a properly set up U-Tube overflow, it sucks, they can cause a flood. I have yet to have complete falure but have lost siphon in one of the two tubes. Never again will I go that route. Murphys law.

If you are losing siphon in one of the tubes, something is not set up correctly (not enough flow?) A U Tube should never lose siphon. If one U Tube will handle the flow of the pump, you are better off running that way.

 

[KEstep]

I have had several tanks with HOB overflow u-tubes. There was one in particular on a 75 that I didn't touch for a year and it never broke siphon. On the other hand I had another overflow on a 55 gallon that would continually lose siphon every week or so. Most of the time U tubes are safe as long as you pay a little attention to it. I never could understand how some of my clients would not look at their tank until there was water on the floor. It also helps to remove the sponge prefilter. If it gets clogged with detritus it slows the siphon and raises the water.

 

[heuerfan]

Used an amiracle overflow box rated for 600 gph with mag5 return, no problems. Just have to clean utube if it gets a lot of algae buildup.

Currently using a lifereef overflow box rated for 700 gph with eheim 1250. I was using 1/2 vinly tubing with the eheim 1250, with this setup i was getting bubbles trapped in the u-tube. Somone suggested i used a larger vinyl tubing, so i changed it to 5/8 and no more bubbles accumilating.

If you happen to lose siphon on the overflow box, all the water from the sump will be pumped to your tank and disaster will happen. BUT if you make sure that your tank can handle all the water from your sump then you will never have a problem. My return pump section is about 5 gallons and i have my lifereef overflow box set at its lowest point allowing room for more water in the tank with out flooding.

Drilling is the best option but i did not like the look of the big overflow in the tank, and don't have the money to have a tank built with external overflows yet

Good luck.