Plumbing question: slurpin' vs. flow

[DonK]

My older tanks did not have overflows (were already set up, doing well and close to the wall) so over time I have drilled them for 1" bulkhead drains (at water level with no overflow, just threaded strainers on inside of the tank). This has worked OK, but, of course, it "slurps" like crazy. With 3 tanks in my office and another just outside it, it is noisy.

I decided to replace to 1" 90 degree elbows (on the drains) with 1" threaded T-s. (I also added "reducers" on the air-side above the water line to end the howlin' that the T-s created.)

I did this on the first tank yesterday (a 240 FOWLR with 3 drains and returns from a Iwaki MD70.) This certainly quiets the drain (no more slurpin'), but DRAMATICALLY reduces the flow. I had to cut throttle back the pump significantly to keep from emptying the sump. Was this predictable to others (it wasn't for me)? (I didn't add any reducers, elbows or anything else that would have predictably reduced the flow.)

My question is: can I do something to increase flow or I am stuck with: (1) slurpin'; (2) reduced flow (as is--NOT really a option); or (3) adding more (quiet) drains.

I was going to do the other 3 tanks this weekend, now I am not so sure. Any advice would be appreciated.

DonK

 

[DonK]

No suggestions--I guess this means that adding another larger drain is the route I'll go.

Am curious if anybody can explain why quieting the drains reduced flow so much.

DonK

 

[vp39]

Have you tried putting an air line into overflow tube? Just something to break the suction is all you need. I have done this with my tank and it is much much quieter and also i have lost no feed to the sump.
Glenn

 

[smokin reefer]

Without a overflow box on your tank, it will be hard to get the best of both.

 

[2poor2reef]

I've never understood the benefit of overflow boxes other than keeping fish (which I don't have) out of your sump. I have always used standpipes without overflow boxes and never could see what the overflows added except space. I've never run bulkheads without standpipes like Don is doing but I've seen a lot of commercial set ups done that way. Seems to me that you only get a portion of the pipe's capacity with a bulkhead/strainer only but his problem is that his flow decreased by changing from an elbow to a T (which he does have open to the atmosphere eliminating backpressure). I don't see how an overflow box would help him but I can see how he could add a 90 pointed down to the tank side of the bulkhead in place of the strainer to achieve a durso effect. Don't know if it would increase flow or not.

Don, do a search on durso standpipes becuase you're partially there. It uses an elbow that goes below waterline and a T with an air valve and there seems to be something key about using a larger pipe and then a reducer at the bottom of the stanpipe. You may be able to substitute the same setup on the portion of your plumbing between the bulkhead and the sump.

 

[Giarc]

Could it be that you have gone from an overflow that functions as a nearly complete 'siphon' to an overflow that has too much air intake? If my hole on the outside of the tank is opened too large you get less flow happening. Perhaps you need to restrict the amount of air getting into the tee on the outside so that it forms a partial siphon?
The other avenue to explore is the reducer somewhere in line between your bulkhead and the sump as 2Poor2Reef said. I would be interested to know what works for you as I'm currently building my 45g tank along the same plumbing lines as you have tried. (Except I'm using dual overflows for redundancy purposes).

 

[SPC]

Don, I presume one part of your tee is out of the water, the reason it dosen't drain as fast as before is you have lost the siphon. Try this, place a pc of duct tape over the opening that is above the water, see what happens? Now poke a small hole in the tape (end of a pencil works) and notice what takes place.
2poor, I think the only advantage of an overflow box is surface skimming, it is much more efficient.
Steve

 

[2poor2reef]

That makes sense Steve. My standpipe skims enough for my invert-only systems but I can see how a long line of teeth would be better for more heavily stocked/fed tanks. Don, please post feedback as to whether these suggestions work. There are a couple of us who are plumbing new systems who are watching this thread. I was planning on T'ing also but had planned to use an adjustable nipple on a cap on the high side of the T.

 

[Anonymous]

My 20g had a standpipe, tank was drilled in side, with a pvc 90 pointing up as the overflow. It worked great, I used a T on the outside, to keep the slurping noise down, only bad thing was when a snail climbed into the pvc, caused a small flood. Some form of grating or slots is much safer, I started using windowscreen. L8r mega

 

[Anonymous]

Install a duroso mod on the back of the tank, I did this with mine and it worked great, just make sure you do it right, dont want to flood your house. L8r mega

[ July 08, 2001: Message edited by: MegaDeTH ]

 

[DonK]

Glenn:

I am not sure what you mean. Tank is drilled in back at top with threaded strainer on the inside of the tank (there is no overflow). You mean push the airline through strainer into the overflow tube (with part of it still hanging outside--to the top--of the strainer)?

DonK

 

[vp39]

Don,
Yes you have the idea. But you will probably have to close off one side of the tee. Or just try it first on another tank.
Glenn

 

[Larry Grenier]

Here is a design I'm about to use on a drilled tank I acquired. Your advice, comments, criticisms...
Click here

 

[SPC]

Larry, your inside elbow is going to make alot of slurping noise with the opening at water level. Look at the Durso or Stockman design and I think you will see what I am saying.
Steve

 

[DonK]

Thanks for the replies. Why slurpin' and siphoning didn't occur to me I don't know. It makes perfect sense now that you suggested it.

My drains look like Larry's except that on the inside of the tank there is no elbow (with surface skimming) rather the bulkhead is at the water level (with a threaded strainer). (Had I been more clever or known about this BB 3 years ago, this is not the situation I would be in.)

I have closed top of the T with duct tape (as suggested by Steve)or threaded plug , and this increases flow to within an RCH of where it was AND not surprisingly brings the slurpin' back with it.

I have yet to experiment much, but even small drilled holes in plug at top of T reduces (or ends) slurpin' but reduces flow with it. I will fool around with different size holes to see if I can reach an acceptable compromise.

Thanks,
DonK

 

[SPC]

Don, if you place an elbow on the inside,like Don, but turn it down instead of up, you should eliminate the slurpin. Now however you will have eliminated your surface skim ability. If you build a small skimmer box that encloses this inside elbow you will bring back this skimming ability and in essence will have what I think you are looking for.
Steve

 

[New65Reefer]

I fought a terrible 10 inch standpipe for days before someone here gave me the answer. I don't know who that person was, but they haven't chimed in with their miracle cure yet. So I'll tell you....

Add a gate valve to your overflow line, right in front of your sump. I actually added a ball valve, but it takes more time to adjust (one day). Sounds like a crazy idea, but when you open the valve fully and then slowly close it, it hits a point where it backs the water up the overflow line ever so slightly. This causes the line to be full of watre and very little air, hence no slurping or gurgling.

This actually works without restricting water flow. It does change the water levels in your tank and sump slightly though. And if you close the valve too much, it will suck your sump dry.

This valve actually works well. Once you get it to the right spot, just forget about it.

I too was skeptical, but try it. The valve only costs a few bucks and you will love the results.

And I can hear the people out there right now saying do not restrict flow into the sump. I said that too, before I tried it four months ago......