Draining too slow

[br1200]

Guys,

I have a problem.
In my new tank (96X36X28) there are 3X 1.5" drains centered in the middle back of the tank.

I currently running a SINGLE HammerHead pump (5800GPH) and the three drains can't keep up. I've throttled the pump to nearly HALF and only then it berly kept up.

My questions:

1) How much can a 1.5" drain handle?
2) what am I doing wrong ?

P.S I've tried Duso & sticking an air tube alone with no avail.

PLEASE HELP



Thnaks
-A

 

[danskim]

According to the calculator on the main page, a 1.5" drain should be able to handle at least 1300gph.
With 3, that's 3900gph assuming you have enough linear overflow length.

What are the dimensions of the overflow?

 

[br1200]

Thanks,

The overflow size is 24X8.
I've also looked at the calculator, and if you put in 5800 Gallons you get 3.15".

If we assume that 1.5" gives you ~1200GPH X 3 = 3600GPH.
That sounds about right.

Which means in my case , that I can NOT just multiply 3X1.5 = 4.5" drains --> which is ~ 12000GPH

Am I correct?
-A

 

[tom obrecht]

I just read your post and can't believe how similar of problems you and I have. My newer tank is the exact size and I had the exact problem you did with the overflow situation. However I had two 2" drains installed. Let me see if I can help (no promises).

First of all the pump you are using is forcing too much water for the size and number of drains you have. Are you using this pump for just the return or is the return pump also a major part of your displays water mov't? Are you pulling 5800gph through your sump? If so what size sump are you using? How far are your drains running before they dump into your sump?

I ended up having to downsize my return pump and adding more internal circulation by means of Tunze Streams and Vortec pumps. Think we need more info before we can give you advice.

 

[i2ik]

I am having the exact same size of tank as yours, except that my overflow is 4x1.5" drains instead of 3, but 2 of mine are closed half way to feed my skimmers. I am running on a Dart pump, which is 3600GPH, so i probably get around 2800GPH without any problem. the water from the 2 main drains are going through my sump which is having 2x1.5" drains. I first had a problem as the pump seem to be too strong. After drilling 2 holes on each durso for the air exhaust, the problem was gone . Not sure if its the same problem, but maybe it could help you a bit

 

[br1200]

Tom, Richard

My sump is 48X44X26. Its the BIG black plastic feed tub.
I holds around 100 gallon.

Tom, you're correct, I'm trying to force too much water.
The HammerHead's porpose was to be used ONLY as a retun pump from sump. I'm using a Tunze (6100 & 7095) for tank circulation.

Richard, I think I'm going to switch my HammerHead into a Dart (3600GPH), that will be enough return flow.

Thanks for your responces
-A

 

[ceophd]

You have to compare the area of the drains not the diameter. If the calculator says you need 3.15" drain, then you will need five 1.5" drains to have more area than required. According to the calculator a 1.5" drain can handle 1300gph.

 

[vegaskid11]

I have two 1.5" drains on my 300 and I have a 5000 gallon per hour pump pushing my returns. I have three 1" sea swirls for return. I do have the return pipe going up the side of the tank and a manifold style return with ball valves on each. I also have a few unions here and there. With headloss from all of that I am at about 3300 gph. I dont have any issues with this thing running full throttle. My overflow is 30" wide.

 

[danskim]

<a href=showthread.php?s=&postid=10704068#post10704068 target=_blank>Originally posted</a> by br1200
Thanks,

The overflow size is 24X8.
I've also looked at the calculator, and if you put in 5800 Gallons you get 3.15".

If we assume that 1.5" gives you ~1200GPH X 3 = 3600GPH.
That sounds about right.

Which means in my case , that I can NOT just multiply 3X1.5 = 4.5" drains --> which is ~ 12000GPH

Am I correct?
-A

No that is not correct.

You have to consider the area of the pipe hole.
3 x (1.5^2)*pi = 6.75pi is what you have.

1 x (3.15^2)*pi = 9.9225pi for 5800 gph.

You don't have sufficient drains for 5800gph.
But you shouldn't be throttling back the pump halfway though... especially after considering head loss..

 

[br1200]

VegasKid,

That looks like a nice setup. But

What pump is that?

Do you think you can push more through the drains?

The math looks about right : 2 X 1.5 @ 1500GPH = 3000GPH

I'll try to put some pics here for better input.

Thanks
-A

 

[tom obrecht]

I originally had a Dolphin 4700 on my return and even throttled 1/2 way back I still had issues. I ended up switching to a smaller pump and adding a couple internal Tunzes/Vortecs to keep things moving. If you are running too much flow through the sump you will probably have other issues as well including bubbles from the sump and poor nutrient removal from my experience. My current pump is a Genx rated at about 1200 gph. Works alot better and uses a ton less electricity.

 

[vegaskid11]

My pump is a Wave 1/4 horsepower koi pond pump. It says it pushes about 6200 GPH but its really 5000. After all of my head pressure its around 3300 GPH or so. My water line is about 5/8 to 3/4 in from the rim. I imagine I could push more but I wouldnt want to get any closer to the rim. I have a loop in my sump for this pump but I run it at full speed anyway.

 

[vegaskid11]

Honestly, the only reason I have such a large return pump is I will eventually have a frag tank and a larger elevated refugium that this will also feed. You really only need 3-5 times tank volume turnover per hour. Also, I have a huge 100 gal main sump which gets half the overflow and a 150 gallon water change sump that gets the other half so I dont have an issue with bubbles.

 

[br1200]

danskim, thanks for your math.
I'll have to change to a smaller pump (4000GPH).
Regarding head loss and 90's, Its only 5ft head & one 4 way manifold into the tank. I would guess tha the pump pushes around 4500 ~5000 gph currently.

Well here I go to sell my NEW HummerHead pump, agggrrrrr.

-A

 

[br1200]

I went ahead and changed into a Baracuda pump which is smaller only 4200GPH.
I have about 12 ft of head total, so i figured the tank has about 3500GPH.

When I plugged it in today, somthing very intersting happend, instead of using the three drains ONLY two are in use and the thierd one is STARVED. NO water is going through it at all.

I tried to changed the hight of each drain, but still in uses ONLY two at full capacity.

Can I leave the third one as reserve? will it kick in in the flow increases?

Is there a way to fix it?

Thanks
-A

 

[br1200]

I just had an idea,

Can I combine all three drains into one 3" durso on top?

Thanks
-A