My 1.5 drain isn't keeping up with my Mag 9.5

[clsanchez77]

My previous setup was a 65 drilled in the back like yours but a few inches lower. I had a 1.5" bulkhead without the elbow, then outside the back of the tank, elbow it upward 4" and into a 'T' fitting with a drilled cap 1.5" PVC pipe to the sump all on a Gen-X MAK4.

I think I understand what is going on here but have tried unsuccesfully 4 times to type it correctly, so let me get my thoughts together.

Chris

 

[kalare]

<a href=showthread.php?s=&postid=6541911#post6541911 target=_blank>Originally posted</a> by smp
The drain was above the water line.
I experimented with how much air was getting into the drain by 'gapping' the cap and letting through various amounts of air, none of it helped.

Other guy is right. Just gapping it isn't going to stop enough airflow. You need to secure the cap on there with a small hole in it. Caps are like 40 cents, just buy a couple and experiment. There is a big difference between a secured cap with a small hole and a cap that is sorta half on. I bet if you shot water out your cap that is half on, it would come out ALL sides. That means it's sucking air down ALL sides, which is still too much air.

 

[kbmdale]

I guess this is where you are at..

If you have the cap on with no hole, the drain will start a siphon that drains the tank to the bottom of the elbow..

If you gap it as your calling it. The pump over runs the overflow.

So in conclusion somewhere between fully sealed and half capped there is a happy median....

Am I right

 

[clsanchez77]

As stated before you want a controlled siphon and I think LobsterOfJustice and kbmdale have had the best ideas so far.

You need to get a controlled siphon. I dont think removing the elbow is a good idea however, Ill explain.

If you have the cap sealed, you will get a true siphon and the water level will try to stabilize at the lip of the elbow, however, air will vortex into the pipe and break the siphon and the water level will rise until the siphon is created again. The result is the water will fluctuate and make the famous toilet bowl sound (siphon flow will run quite, the gravity flow will flush).

If you remove the elbow but keep the cap and just have the bulkhead, you get the same siphon and siphon break cycle at the top of the bulhead.

If you remove the cap, you will get true gravity flow (elbow is irrelveant in this case). In this case, the water level will have to 'build up' and create enough head to drive required water flow thru the bulkhead, this will suck in lots of air and make the constant gurgling sound, however the water level will be stable.

If you place the cap, either drill the hole or cut the slot, you can control the 'siphon' effect, thus control the water level. Unfortunatly, to drop the water level below your bulkhead will require a true siphon, anything below maybe too close to the bottom of the elbow and you will get siphon breaking. Even with the advise offered, I think the best you can do is keep the elbow and aim for just a hair over the top of the bulkhead.

Again, if you remove the eblow, you will allow air to vortex into the bulkhead and break the siphon control.

Did I confuse you more, or anyone else more, or maybe myself more

 

[clsanchez77]

kbmdale, you beat me I was trying to explain this as simple as you put it

BTW, an overflow box would afford you a little more 'play' with the siphon as the box would hold the tank water level. You can probably fassion something out of 1/8" acryilc, maybe 2"depth x 4" height and 3" wide? Maybe this is not feasable for you but it would certainly make this less of an issue, plus you would be drawing water from the surface (where most organics are located) as opposed to underneath the surface.

 

[clsanchez77]

ran some quick numbers, guessing that you are running about 550-600gph with the setup, your water level at gravity flow will be about 1/2" to 3/4" above the top of the bulkhead. So if you are getting too much air, the water level should not rise above this (unless you block something).

 

[Dave 32]

This might be a dumb question but why is the elbow facing down don't you want to skim water. I have had a similar problem with my 120 gal and 1 " bulkheads with a mag 7 I run a gravity drain and runs ok but can't handle a mag 9 and would love to get more flow I tried running 1 1/2 off the bulkhead w/ the tee I run an open pipe staight up and that stops the slurping. Are you guys saying if I cap the tee and drill a hole in the top I can get more flow without slurping an no chance of overflow in the case of power out?

 

[Dave 32]

I think a mag 9.5 runs about 850-900 gph.

 

[smp]

<a href=showthread.php?s=&postid=6542081#post6542081 target=_blank>Originally posted</a> by kbmdale
I guess this is where you are at..

If you have the cap on with no hole, the drain will start a siphon that drains the tank to the bottom of the elbow..

If you gap it as your calling it. The pump over runs the overflow.

So in conclusion somewhere between fully sealed and half capped there is a happy median....

Am I right

No.
I understand what both of you are describing, maybe you aren't understanding my 'gapping' thing.
The hole doesn't have to be a perfect circle. The goal is to let in enough air to control the siphon (we both agree on this, maybe I was calling it the wrong thing earlier though). By 'gapping' I mean that I am slightly raising the cap, on a slight angle so that only a sliver of air gets in .. I can variate the size of the slit by moving the cap slightly .. you see? Gapping, maybe a stupid thing to call. Nonetheless, I don't see how this isn't the same as drilling a hole, we're accomplishing the same thing, right?
So are we on the same page?

 

[kbmdale]

Yep thats what we're saying. The size of the hole in the cap is what will regulate your flow. If your getting to much flow to the sump make the hole bigger, small adjustments until its right. If your not getting enough flow to the sump the hole needs to be smaller.

If you want to test this take some masking tape and cover the hole real good. Then take a PIN and make a hole in the tape over the end of the pipe. Keep making the hole bigger till it evens out.

 

[static80]

<a href=showthread.php?s=&postid=6541657#post6541657 target=_blank>Originally posted</a> by smp

I still don't know what gives because the inside of the bulkhead is more than 1" for sure, probably 1.3" or something after the threads and what not.

A 1 1/2" threaded bulkhead should should be for 1 1/2" pipe and have 1 1/2" female npt threads, so the hole would be closer to 1 7/8" wouldn't it?

Am I wrong?

I think you've measured the bulkhead's outside diameter, but when measuring plumbing you need to measure the inside of the pipe.

 

[clsanchez77]

why is the elbow facing down don't you want to skim water

if you face the elbow up, you will not get a Durso effect as air will enter the pipe with the water. I wonder if this is a better stockman application, although those are not very common.

I think a mag 9.5 runs about 850-900 gph.

He has almost 20' of 3/4" vinyl tubing in the picture on top of 3' lift and Mags loose a lot of flow with head loss. But you are right for closed loop applications, they max out a 950gph with no vertical lift and 1.25" diameter PVC pipe closed loop with not excessive length.

 

[npaden]

smp,

Let the water go up past the elbow. It looks like you still have room before you would overflow the tank. What should happen is the water level will rise to about 1/2" to 1" above the top of the bulkhead and then stop.

Just make sure that the sump can handle the extra water when you turn the pump off or have a power outage.

FWIW, Nathan

 

[npaden]

Also you could increase the flow more if you used one of the sweep T's that they use for drains. It will have a sweeping drop instead of the right angle on the T you are using. Just be careful to make sure you get it glued well because you will have less surface area to bond the way the drain fittings are made.

Here is an example:

 

[kbmdale]

But your gapping method is obviuosly not working. It is still letting in to much air. There is no way to seal the cap the way your showing in your second pic to controll the air flow. Your thinking the little part that is stickng up is the only entry point for air, but its not the cap is letting air in all the way around cause its round and your putting it on oblong.

try the tape thing I just described.

here is a pick of my 1 1/4 durso that keeps up with my iwaki 40rxt (1100 gph @4head)

notice the 2 holes. One didn't throttle it back enough to keep it from slurping.

here is the 3/4 pipe durso that keeps up with my mag 7...

 

[Dave 32]

The sweep tee is a good idea thats what I put on mine it made it flow alot smoother

 

[npaden]

And lastly you can increase the flow by using a larger elbow on the inside of your tank. I have the same type of drain on one of my tanks and I use a 1" bulkhead and then on the inside I use a 1" to 1 1/4" elbow with the 1 1/4" part as the opening in the tank.

I think you could get a 1 1/2" to 2" elbow if you looked around. That almost doubles the area of the water flowing into the elbow.

 

[smp]

Well I'll have to eat my words!

You're right, this is more of an exact science than I thought. My technique was lazy and sloppy and I wasn't getting the desired mix, or control.
I taped it up as suggested, poked a hole and now it's holding steady at:

It's right over the whole thing, the entire elbow is under water. I'm no comfortable with this because it feels like it could overflow the tank anytime .. so I'll have to do something else to slow it down a bit, but I'm almost there.

Thank you very much!

 

[kbmdale]

Just make the hole alittle smaller and that will speed up the rate of water going to the sump. It is a very exact science. 1/16 hole size could be the difference between Flood and Slurping...


glad to help....

 

[smp]

<a href=showthread.php?s=&postid=6542600#post6542600 target=_blank>Originally posted</a> by kbmdale
Just make the hole alittle smaller and that will speed up the rate of water going to the sump. It is a very exact science. 1/16 hole size could be the difference between Flood and Slurping...


glad to help....

I'm really amazed I don't hear about more floods this way!
I mean, I wanted to go the drilled tank route so that I could AVOID a swamped floor!


Now onto my NEXT problem!

LOL

(joking, I can think of a few things to do to make this quieter, this was my trial run .. it's SO loud!!!)