How much water pressure loss at 90 degree elbow?

[Thorsx]

I ask the question because I have been fighting a long and bloody battle to try and get my Red Sea Berlin skimmer to produce foam.
1. Replaced Rio 2100 pump with Mag 1200 pump
2. Mag pump with pre filter was to big for sump so I elected to run pump inline and out of sump.
3. Also added kent 3/4 Turbo venturi for more air flow.
4. Assuming pump would produce lots of foam I used PVC with ball valve and quick disconnects. This means three 90 degree elbows were needed to direct water up, over and into the skimmer (Skimmer is about 16 inches high). Berlin claims 500 GPH is needed to run skimmer. So I am wondering how much pressure is left from my 1200 Mag after maybe 2 feet of 3/4 PVC and three 90 degree elbows. Bottom line, I still have no foam after 2 days with the new set up. Prior to this I got 1 cup of light green "Tea" once a week from Rio and stock skimmer.

[NorthCoast]

Have you checked out the calculator link:

http://www.reefcentral.com/calc/hlc.htm

this may help if you plug in the numbers.

Later,
NC

[Thorsx]

According to the calculator I would be loosing 87.68 Foot head or 37.89 PSI with my set up. Not being a hydro engineer, I am not sure how that affects the final GPH reading at the skimmer. My Mag 12 is rated at 1200GPH and 500 GPH is needed at the skimmer. Anyone know the math? My latest mod is to chip away some of the inner plastic tubing in the collection cup of the skimmer with pliers. Finally have just a touch of dry foam oner the broken edge.

[NorthCoast]

I actually have a Mag1200 running a 4' skimmer. I have 3/4" pvc and (4) 90 degree bends between pump and skimmer. I have a 1/2" pvc gate valve for my air intake.

How large is the air intake opening? You might not be getting enough air mixed...

Just a thought,
NC

[Thorsx]

The air intake on the Kent Venturi looks like it is about 1/4". I am debating on weather a 90 degree elbow placed between the venturi and the skimmer might be the problem. The elbow is needed since space is limited in the sump. I would be curious to see this 1/2" air intake with a gate valve. I may try running flexible pipe this weekend to eliminate 2 elbows.

[NorthCoast]

This is the best photo I've currently have loaded:

http://ncoastreef.homestead.com/files/skimmer1.jpg

I am completely starting over with my site... sorry. :( long story. I hope you can get the jist from this pic?

Later,
NC

[Tommyc]

Thorsx, help me visualize this. I also have a red sea skimmer and added the venturi mod, but I'm using a Mag 9.5.

You are using PVC with three elbows to take water out of the sump, feed it to the pump, and then feed it through the kent venturi into the skimmer, right? My mag 9.5 provides more than enough power so I can't imagine that yours would lose enough pressure on the intake side to cause your problem.

If this is a silly question then forgive me in advance, but did you unscrew the old intake from the base and then unscrew the screw in nozzle that's behind it? Your Kent mod should be screwed directly into the base of the berlin.

If you left that old nozzle in there, that'd be your problem. My problem was just the opposite...to much wet foam. I had to throttle my new air intake way down. Others have had the same experience. It also takes a couple days for a newly cleaned skimmer to begin producing foam again, but with your larger pump, I'd bet you'd have plenty of water flow even with your elbows on the intake side.

[Wazzel]

Thorsx

Somthing does not look right in your pressure loss. It seem to be kind of high. I also have a mag12 in my tank so I have a copy of the pump curve. Once you get over 15 ft of head loss the pump will not pump. This is called shut off. At you head loss the pump would not pump and eventually burn up. Based on the information you put in I would say you are probably running 500-700gph.

[Thorsx]

Here are the measurements I entered to calculate head loss (still not sure what that means).
Friction Factor: .016
Vertical length: 5 feet (based on four 15 inch sections 2 for pump intake 2 from pump to skimmer)
Horizontal length: 1' 6"
Pipe Diameter: .75
GPH: 1200
90 degree elbows 7 (4 from sump to pump, 3 from pump to skimmer)

29.39 Ft Head or 12.7 psi
Elivation head loss 5 ft head
Total head loss 34.39 ft head or 14.86 psi

My next thought is to eliminate 2 elbows by running flex pipe from pump to skimmer. That would bring down total head loss to 25.54 ft head or 11.04 psi. A last resort would be to put the pump in the sump but I want to avoid this because I live in Florida and things get hot enough.

Looking at the photo I see the same pump pushing water up a much greater vertical than my set up. Granted, however there are only 3 elbows. Also I can not see how water is getting to the pump from the photo. And if you are correct Wazzel, that I have 500-700gph, then things should be working now.

Are there any sites that explain head loss, foot heads, and psi as it relates to gph?

[Thorsx]

I replumbed my skimmer again today. The plan was to try flex pipe for water flow to skimmer, but my hose barbs were to big so I just cleaned the skimmer and re assembled as before with pvc. The only difference is that I left off the pump prefilter. I also snipped off more of the inner plastic in the collection cup reducing the hight by 1/2. Now I get a fairly consistent dome of foam at the top of the inner tube. On occasion a small bit will overflow into the collection cup. This is the first time in years that I have seen foam overflow.:)

[NorthCoast]

Thorsx,

Congrats! May your skimmer cup runith over (but no on the floor)! There is nothing like fresh skimate to awaken the senses... ;)

You are right about water getting to the pump in the photo. I had it disconnected when the photo was taken (best example I already had posted) :) There is a bulkhead in the side of the sump and the plumbing runs horizonal into the pump. As to the elbows... I'm still learning to count, but they gave me a minor in math and electrical engineering anyway. :D

Later,
NC

[Wazzel]

Thorsx

I am glad to hear that you skimmer is working. I guess only reefers can be excited about things that produce crap. Not trying to step on some toes, but I can see that some explanation on pumps is needed here. A pump is a really dumb machine. In a give system it will run at one and only one flow. This point is determined by the system and it's configuration (each valve position is a different system). In order to figure out how much you pump is pumping is going to take a couple of tries. The program in the calculations section shows the system losses for a give flow. In your manual that comes with the pump you get the flow for a given head loss. The numbers you are showing in you calculation are correct, but a mag 12 can not put out 34.4ft. It will no longer flow at 15ft and above. To determine what you are actually pumping use the program in the calculation section and pick a flow. I would look at the informatio provided in the manual and pick one that is in the mid range of the pump curve. If the system head loss from the program equals the head loss on the pump curve, congrats you are a great gusser. If the head loss is higher then you have to try less flow, if the head loss is lower then try more flow. Play with it a couple of times and you will understand.

Later

[Thorsx]

My Mag 12 didn't come with any documentation. I guess I will try and see if Mag has a web site with the info you are taliking about Wazzel. My latst calculations with JUST the return line to the skimmer were 15.07 frictional foot head which is just over the 15 you claimed the pump would not handle. I am just barely producing some foam but since this skimmer has never produced foam before I am exstatic!!! I am considering using 1" pvc instead of 3/4" pvc the 1' would lower frictional head loss to 4.54. That should blow the lid off the skimmer and then I could cut back the water flow with a ball valve. Thanks forr all the help !

[Wazzel]

Thorsx

The manual that comes with the pump is not all that great. The mag drive web site is www.pondmaster.com. They do not have an on line manual to look at though.