Durso flushing problem..

[ScottWV1]

I apologize for the repost, but for some reason my version of this BB has not updated. I made a post 5 days ago and I still can't see what I posted! Aragorn even responsed to my post, but I can't see his response either! What is up with that? BTW, I have made other posts and replies to existing posts and see the updates pretty much in real time. It seems to just be this one thread....

Oh well, if you check out the other current thread on the Durso standpipe started by Aragorn, you can catch up on what's going on. Anyway, the pumps I am using are the Mag7 and a Mag9.5. Including head, both are pushing between 400-500 gph.

The current suggestion is to create a bigger hole in the standpipe cap, but when the current hole is fully open, my water level rises so high that I'm afraid it will overflow the tank. As I screw in the airline regulator valve, it goes from 'too high' to 'flushing'.... no inbetween!

Any advice?

[mgk65]

Scott:

Maybe your pipe size at the ell is too small and not letting enough water through?

I made the Stockman model of the Durso Standpipe and have had great success.


mgk

[This message has been edited by mgk65 (edited 02-14-2001).]

[ScottWV1]

mgk65 - care to elaborate on what the 'stockman' version is? My elbow is 1", while the remaining portion of standpipe is 1 1/4". Unfortunately, my bulkhead is only 1" so I am limited by that (realize my bulkhead is drilled in the back glass just below the tank band/frame). So, this is modified from the original durso design (bottom drilled bulkhead).

Thanks for the response -

Scott

[mgk65]

Scott:

The Stockman version is shown here: http://home.att.net/~rstockman/overflow.htm
(He's another guy from WV, btw)

Anyway, I do not believe that that is an option for you since you have a drilled aquarium.

I am trying to visualize your setup. Your tank is drilled in the back with a 1" bulkhead going to an overflow? Can you explain this some more?

I'm pretty new at this, but I still feel that it is a matter of flow through your plumbing.

If you make the vent hole smaller, that allows less air into the pipe, slowing down the water flow. This allows the drain to be nearer equilibrium.

However, if you open up the vent, the water level rises. This could be creating turbulence with enough back pressure to keep the water from draining fast enough.

Tough problem.

Possible options:
- make the standpipe bigger to 1.5"
- make the elbow bigger to 1.5 or 1.25"
- make the drain to the sump bigger

Although the bulkhead is limited to 1", the flow before and after it could be causing you the problems.

In remembering my flow physics:
- A narrower pipe will have higher velocity, but less flow.
- A bigger pipe will have more flow, but lower velocity.

More flow is better.

Sorry, I cannot be of any more help.
mgk

[Aragorn]

Scott,

Did you get my email? BTW, you work for Nortel, eh? We deploy Nortel where I work. Both Norstar and Meridian phone systems along w/ Baystack Ethernet Switches.

------------------
"Remember...Wherever you go...There you are."
Buckaroo Banzai, circa 1978

[ScottWV1]

mgk - thanks for the explanation on the stockman design. That is a slight twist to the durso - I like it!

My tank is drilled in the right top corner of the back glass, about 1.5" below the tank framing and about 3" in from the tank side. If you are familiar with the durso design, picture the elbow at the top of the design... where that elbow would typically go into the 'tee' of the standpipe, mine goes into the bulkhead fitting... on the back of the bulkead is a fitting converting the 1" bulkhead into a 1 1/4" tee... at the top of the tee is the 1 1/4" cap and at the bottom of the tee is an insert fitting converting the hard pvc pipe to 1 1/4" flex tubing which simply runs to the sump.

At the top of 1 1/4" cap, I have drilled a hole just large enough to push an airline valve into (as per the stockman and durso designs).

I am pushing 400 gph in one tank and 600gph on another. With the valves closed I get 'flushing'. With the valves completely open, the tank raises so high that I fear overflow and shut down the pump or put my finger over the air valve and the water drops. Would this not mean that the hole I have is plenty - I just have to find the setting in between that is right (but I can't seem to find it!)? or could I still not be getting enough air?

Thanks -

Aragorn - yes, I got your email - thanks. All I can say is that I will drill a larger hole and see what happens - my head tells me that is no different than having the valve completely open and I expect the tank level to go up faster... but maybe there is some airlock thing hap'n...

As for me working at Nortel - well, I've been with them since college (going on 16 years with them) and just got laid off Jan 26th. [img]/ubb/frown.gif[/img] They are a great company and I really enjoyed working for them - unfortunately, my area was hit especially hard and I was in the wrong place at the wrong time.... very said. Especially bad timing because 9 months ago I moved 400 miles away from the Nortel offices (I became a fulltime telecommuter) to a very small, remote, poor WV town to raise our now 8 week old daughter near her grandmother....

I'll keep you posted on the standpipe mods...

[Aragorn]

Scott,

I thought the same thing. Had the air hole COMPLETELY open and still had the problem! Then I drilled an additional hole and the problem went away. Sorry to hear about the lay-off buddy. Keep me posted, OK?

------------------
"Remember...Wherever you go...There you are."
Buckaroo Banzai, circa 1978

[mgk65]

Scott:

If you want to play with it, try taking the cap off of the top of the standpipe and see what happens.

Maybe you can then manipulate the opening easier.

mgk

[Aragorn]

Scott, any luck?

------------------
"Remember...Wherever you go...There you are."
Buckaroo Banzai, circa 1978

[ScottWV1]

Well I'm still stumped! No matter what I do (more holes, larger holes, tape over holes, etc..) it all comes down to this... with the only hole in the endcap being the hole that very snuggly holds the air valve fitting, and the air valve fitting completely open, my tank overflows. With the air valve completely closed, constant slurping noise... in between is flushing (only the water line gets higher as I open the air valve).

I'm beginning to think it's the design itself. The original durso standpipe is 1 1/4" reduced to a 1" bulkhead and then 1" flex tubing (I imagine..) to the sump. My design, on the other hand starts with a 1" bulkhead and then increases to 1 1/4" to the sump.

Maybe I should redo the standpipe in 1" or 3/4"? What do you think?

Again, thanks for all the help -

[merlin701]

Afternoon folks. I have been doing some research on this and have repeatedly run into the same problem.

If you get a flushing action it is due to a lack of air. When your standpipe can't take in enough air it causes a siphon. This will siphon your overflow to the bottom of the elbow letting more air in and makeing lots of noise. Too much air and you don't get enough suction causing your overflow to fill too high and or possibly overflowing your tank.

My current instance is the same as yours. I drilled the hole big enough to accept an air line fitting but when I inserted the fitting it chocked off the air too much, thus the flushing action.

Quick solution........Drill your hole larger and put a piece of duck (duct?) tape over it. Then take a nail or screw and slowly open up the hole until you get the desired effect.

------------------
Shade & Sweet Water
Brian


Brian@reefland.com

[mgk65]

Scott:

Does yours look something like this?



this is from Richard Durso's website.

[This message has been edited by mgk65 (edited 02-18-2001).]

[CliffJahner]

Hello,
First time posting here, couldn't help but notice your delimma. I think after reading about the Dursou(sp) standpipe, I think your problem is that your top elbow is too small, it should be 1 1/4" like the rest of the standpipe. I think the way it works is that your bulkhead at the bottom is supposed to be the limiting factor in flow, that is why the standipe is designed larger. So now with the flow limit on top it restricts the flow into the standpipe, and standpipe is now emptying faster than it is filling causing the gurgling sound. So in affect make the top the same size or larger, not smaller.
Hope it helps.

[Ceorl]

Bingo! [img]/ubb/biggrin.gif[/img]

I'm a first-time poster and a newbie reefer, but I know my fluid mechanics ...

The flow thru the elbow is at a particular velocity.
This causes a local vacuum relative to atmosphere, sucking in air.
This lowers the water level in the standpipe.
The restricted flow at the elbow causes too high velocity, causing a rush of water to keep up with the average flow rate.
The rush of water is too much, so the velocity goes down, less air is sucked in, the water level rises. It gurgles.
To achieve steady-state (non gurgling) operation, the air hole has to be very precisely matched to the rest of the system. One salt crystal would unbalance the system.
By restricting the flow at the bottom of the standpipe, the average flow rate is controlled, so the air hole just needs to be close enough to allow the water level to find a steady height which matches the flow rate.

The overall friction and height difference from the tank to the sump (actually the pipe outlet, if above the sump water level) determines the flow rate, but the bottom of the standpipe must be restricted relative to the intake arrangement to prevent gurgling.

So make the change to the inlet arrangment so it doesn't restrict flow to prevent gurgling. Your flow rate should be about the same as before.

For more flow: You're probably stuck with the bulkhead, which has the biggest impact on flow rate, but you could increase the tubing / pipe size from the bulkhead to the sump and get a marginal increase in flow rate.

This is fun. [img]/ubb/biggrin.gif[/img]

[ScottWV1]

mgk, yep, my design is very similar except without the external syphon/overflow box - my bulkhead is directly in the back glass of the tank.

Well, I've tried a smaller return line to my sump. Here's what I've tried - kept the 1 1/4" connection to the bulkhead but reduced down to 1" at the bottom of the tee (kinda like simulating going through a 1" bulkhead at the bottom of the standpipe). Obviously I can't do anything about the 1" bulkhead in the back of the tank glass, but suffice it to say that I still cannot get the overflow regulated. If I throttle down the return line ~25%, I can get the water level to stabilize to the point where it only goes through the flushing cycle about once an hour. Problem is that if I shut down the pump, wait 30 seconds, and turn the pump back on, the tank fills too fast for the overflow and it would overflow the tank before it settles back out again...

I guess at this point, the only think I have left to try is what Cliff suggests. Since my overflow is limited by the 1" bulkhead in the back of the tank, I will replumb the standpipe with 1" pvc and then reduce down to 3/4" flex tubing going to the sump. If this doesn't work, I will be out of my mind! I hate reducing the overflow all the way down to 3/4"! I'm afraid it will not be able to handle the throughput I want - hell, at this point, it aint working anyway -

Thanks for the suggestions, I'll keep you all posted.

Scott

[scubadude]

FWIW I have a 90gal W/ Durso Overflow 1" bulkhead and 1.25 piping and mine needed final adjustments but appears to be working fine now too....I also thought mine was gonna overflow in the tank but it just took a while for everything to level out...Good Luck HTH

[ScottWV1]

Well, thanks for the replies/suggestions - here is the latest!

I built the standpipe completely out of 1" pvc (to match the bulkhead fitting) and then about 8" down from the bulkhead, I reduced the pipe diameter to 3/4" and used flex tubing to the sump (about 5').

Well whala!!! Now it works like everyone has been telling me it should! I apologize for wasting everyone's time on this... Using the air valve I am able to adjust the water level in the overflow chamber to be about 1.5-2" below the water level of the tank (also about half way up the elbow fitting as richard durso suggests).

BUT!!!! Now I have the problem that if I simulate a power outage and then turn power back on, the overflow has a real hard time priming itself. I only have enough water in my sump so that if the water level raises in my tank, it can only rise slightly ABOVE the edge that the glass canopy rests on - at this point, the pump sucks in air (blowing bubbles into the tank).

Within a minute or two, the overflow primes itself and things even out. Obviously this is not acceptable because ultimately I want to have an abundance of water in my sump for evaporation purposes, and during a power outage, there is no telling how much water will overflow during the period it takes for the standpipe to prime itself!!

So, what is the key to ensuring the pump self primes quickly?

[This message has been edited by ScottWV1 (edited 02-19-2001).]

[Mobious]

If I may ask what does this stuff do? Flush water into your sump?

[ScottWV1]

Mobious, simply put, this is a design used in taking water from the tank to a filter/sump/refugium below the tank. It is based on gravity feed and the concept/theory behind it is to improve on a basic drain design and to reduce slurping noise.

Check out this website http://www.rl180reef.com/frames.htm

Scott

[ScottWV1]

Any ideas/thoughts on the priming/stabilizing problem??

Aragorn, mgk, Brian, CliffJahner, Ceorl, scubadude?????

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