How risky is it to use a hang on overflow on a non drilled tank?

[Shane and John]

..So we have a 120 gallon non drilled tank...we really want to add a sump and refrugium...we have been told the only way is to use a hang on back overflow...are there alot of risks involved with doing this??If so...what are they??.....We need to get a new skimmer,but we dont want another hob model...so we are curious is we should get one that will work in a sump ,if we can add one,Or if we should even concern ourselves with that... if its not a safe or sane option...

 

[ronj]

i have never personally used a H.O.T. overflow, but i have heard a lot of horror stories about them..i decided i would never use one....maybe some people that have had success will chime in

 

[mmkeeper]

No different than a reef ready tank. Just make sure that you adjust the sump water level so you have enough room in it if the power goes out.

 

[trido]

No different than a reef ready tank. .

Not true at all....A reef ready tank wont lose siphon during a power outage causing all of the water in the sump to overflow the tank when the power comes back on.
Having said that. Many reefers have had long term success using HOB overflows. Alot of overflows have a siphon prime tube that require a power head venturi or an aqualifter pump to help with air build up and to possibly even reprime the U-tube in the event of losing prime during power outages. Thats not saying it will definately lose siphon but it is alway possible. HOB over flows are a risk but with diligence can be fine. If you live in an apartment I wouldnt recommend it. If you read a few recent threads you will see why.

 

[dlove18]

I've been using a CPR overflow for a few weeks. I don't have tons of XP with it. I don't see how it can fail unless the aqua lifter pump goes out after a power outage.

if the lifter pump fails, you could lose siphon. then the return pump would overflow the display. the chances are prolly about the same as a piece of rock falling and breaking the glass.

the more likely scenario would be the return lines siphoning water from the display when the return pump shuts down and overflowing the sump. the simple answer to this is keep the return outlets close to the surface so that air breaks siphon before the sump overflows.

I don't see the overflow (if done right) being any more dangerous than a drilled tank. there are several points of potential failure on each that could make a big mess.

but, my next tank will be drilled. =]

dan

 

[jedimike]

I've used a h.o.b. overflow for a couple of years now. They aren't ideal, but they work. I've never had any major accidents that were caused by my overflow. Also, they keep their syphon when they lose power.

The two big things that can happen...

1. You lose syphon on the tubes - you empty your sump into your tank, which then goes on your floor. Very bad! My U-tubes will slowly lose syphon over time and I have to reprime them every now and again when I notice the tank level rising. I don't use the auto-primer power head approach.

2. During power outage you get reverse syphon and your tank will empty into your sump. The tank will only empty to the point the syphon breaks, so most people drill a tiny hole just below the water line on the return to prevent this. This isn't even a concern as long as you keep your water level in your sump low enough to hold the extra few gallons of water.

All in all, it's pretty easy to maintain. The benefits of a sump/refugium are well worth the small risk.

 

[Herefishyfishy]

HOB overflows work just fine with a couple things done to make sure you don't have a flood in the event of power interruption. Here are some in order of importance:

1. Siphon break on your return lines
2. Large enough sump with a good safety factor
3. a reliable means of restarting siphon such as an air hose hooked up to your returns input or a newer aqua-lifter pump
4. settings on overflow to proper level.

I used a HOB CPR brand on my 90 reef in an area with frequent power outages and it worked fine. Get some help from one familiar if these don't make sense.

 

[DonW]

I'm missing something. A properly installed J tube overflow system should have a box in the tank. It would be impossible to drain the tank with this sort of set up. Using a self primer such as a powerhead venturi or aqualifter will prevent the loss of siphon. I would use a powerhead since the aqualifter will not last very long. When it dies you loose siphon because you have to keep the pump up and in a dry place so it cant back flow the aqualifter hose. With a ph even if it fails the water will continue to be pulled back through the ph preventing loss of siphon. If I worded that right it will make sense.

The best of both worlds is a power head and a float switch in the j tube skimmer box.

Don

 

[GoCougsKev]

Why not just drill two holes in your 120, that is what I had done. I took the tank to Sunset glass in bellevue and it done withen an hour for only a few bucks.

 

[Shane and John]

Thanks guys..it looks like i will be breaking down the tank....cleaning out all of the crushed coral substrate at that time....and then getting it drilled...Wow...thats alot of work,but i think it appears to be my best option...Does anyone know of a glass shop near Puyallup that will drill my tank??What would be the best size sump w/ refrugium for my tank?any ideas on where to purchase it?what size holes do i need drilled and where??

 

[krisfal]

I don't know if I would go to all the effort to drill an already set up tank. If you drill the tank, I think you will still need to create an overflow box (could be inside the tank) in order to pull the dirtiest water from the top of the tank.
I use a HOB overflow and have had no problems. I prevent siphon loss by having an air tube from the top of my overflow box to my pump on my skimmer, it always starts the siphon right back up after the power comes on (I have already experienced 4-5 power outages this winter). I also have siphon breaks in my return line right below the normal water level in the tank. My sump is able to contain the water that will siphon out, until the water goes below the siphon break) when the pumps are shut off/power goes out.

Have you checked with Larsen glass in Puyallup? I used them years ago to order some special glass for a project. Don't know if they are still there though.

Edit: You do not need to buy a premade sump, you can make one from any tank that will fit in your stand, I have also seen them made from rubbermaid containers. Try searching the DIY forum for sumps to get ideas. As far as size I would reccomend the biggest that you can fit, I do not think you can have too much water volume.

 

[TWallace]

I prevent siphon loss by having an air tube from the top of my overflow box to my pump on my skimmer, it always starts the siphon right back up after the power comes on

Maybe I'm not understanding something here. Are you talking about the venturi on your skimmer? Don't you want that to only pull in air? If it's used to start the siphon, won't it be pulling in mostly water once the siphon starts?

 

[krisfal]

Maybe I'm not understanding something here. Are you talking about the venturi on your skimmer? Don't you want that to only pull in air? If it's used to start the siphon, won't it be pulling in mostly water once the siphon starts?

No, it goes to the intake on the skimmer pump. So mostly it pulls in water but it does not matter if it is pulling in air. I used to have it go to the intake of the return pump but occasionally it would cause microbubbles in the tank .

 

[TWallace]

Ahh I see, makes sense now. I have mine setup like that, but with the hose in my return pump intake. Mine doesn't always restart the siphon on a power outage. I may try the skimmer pump instead, as I think it has more power. I'm getting a new Eheim return pump next week, though.

 

[burning2nd]

i use a crp.... for over 2 years now.... works good... just make sure you replace your aqua lifter yearly.

 

[aquarookie]

My CPR hang on overflow has flooded the house twice before I said the heck with it and got a drilled tank.

 

[burning2nd]

why did your CRP overflow?

strange that a bunch of people use it and never had a problem and you did.....

was there a power failure?

 

[DonW]

why did your CRP overflow?

strange that a bunch of people use it and never had a problem and you did.....

was there a power failure?

Not strange at all. I would have to say more people have had a failure than not. Thus the reason why drilling is prefered. Nothing new here.

Don

 

[aquarookie]

why did your CRP overflow?

strange that a bunch of people use it and never had a problem and you did.....

was there a power failure?

Yes, the first time the power failed and the siphon line was plugged up with little feather dusters and whatever else grew in it, so the aqualifter could not restart the siphon. I replaced the airline and everything worked fine until one day the aqualifter pooped out (at the time nobody had told me I needed to replace it regularly) so I came home to a return pump running dry and a big puddle under my tank

I am sure steps can be taken to reduce the chance of that happening (thankfully I learn from my mistakes) but I would still vote for a drilled tank, just to be on the safer side

 

[CarlaW]

If you do the regular maintenance on the aqualifter pump, ie., read the instructions, those pumps seem to last at least a year. I have been using them ever since they came out with them, and have had no problems. I have also been using a CPR overflow on my 80 for about 8 years, and I have no complaints.
It really isn't worth breaking down an established system just to drill the tank, especialy if the tank is doing well!!! JMHO