Tunze 9010 not skimming

[cbrownfish]

Well I am at a loss after 4 days of no skimmate from one of my Tunze 9010's. I have read every thread I could find on similar problems but nothing seems to solve this problem. I recently sent a faulty pump from one of my 9010's back to Tunze in TX and they returned it after repair (thank you again!). Once I received it, I installed it and the skimmer started pushing foam immediately. I will call this skimmer, skimmer A. I have mounted both of the skimmers side-by-side and have them facing the drain line from my display (there is about 2" between the skimmers). The 9010 that continued operation while the other was being repaired, no longer pulls any skimmate. Let's call this skimmer B. Could the side-by-side strategy be affecting the skimmer? Opposing magnetic pull or something?

I have always noticed that one skimmer always seemed to out perform the other but I thought it had to do with the location at the opposite end of my 100 gallon sump. When I take the cups off the skimmers during operation, I do notice that the foam/bubbles in the skimmer A is/are greater than that of skimmer B. Skimmer B produces bubbles but it is unable to push any foam up the riser tube. I thought for sure that it would eventually produce some modest skimmate but it hasn't. So here is a list of what I have done:

1. Check to be sure that the discharge tube assembly is mounted properly and verified that the tube is not pushed too far into the skimmer body.

2. Completely take the skimmer apart and check every connection for leaks and/or obstructions. Made sure that everything was connected properly.

3. Verify that the airline is not full of water by using an air pump to push any water out of the tube on start up. Took the entire air intake system apart and check for bad connections or obstructions. Verified that it was working by blowing air via airpump through the line.

4. Took the motor apart and check for debris, precipitation, and other obstructions. The impeller looked fine and appeared to be in working order. All of the 'teeth' on the propeller are intact as well.

5. Ensure that the skimmer cup is seated correctly. I even switched cups with the working skimmer to ensure that the cup was not somehow faulty or damaged. Skimmer A accepted the cup from skimmer B and started pushing foam.

6. Check the external water level and verify that it is within 1/4-1/2" from the water line. For the record, my sump water level barely fluctuates much due to the large volume and 24/7 top off drip. Both are mounted on the same platform, so the water level is identical.

7. Start and restart the skimmer a few times in case the pump was running in reverse. No effect. I removed the pump and held it underwater to verify that it was pushing water through the venturi.......it was.

8. Inspect the water discharge exiting skimmer A & B. Both appear to be similar.


Is there anything that I seem to be missing or could the pump on this skimmer simply be failing? Both were bought at the same time last spring, making them each about a year old.

 

[rvitko]

I would try swapping the 3130.13 suction housings and see if the problem follows that.

Just a note, the water line is completely irrelevant when using a sump kit, with the stand pipe the water level only needs to be between 4-10" and 6-9" is ideal. It is ideal because you have some room for evaporation to prevent the pump from running dry and the water level is low enough that water cannot enter the air intake system in a splash or surge. The key thing with the sump kit is that water is exiting the pipe.

 

[cbrownfish]

I will swap the nozzles and see if that helps. Looks like an $8 part, so I will order a new one if that is the issue. I will let you know here as well.

 

[cbrownfish]

Duh. I see that you were suggesting the entire housing. I will try that......not just the nozzle.

 

[rvitko]

The nozzle is the main thing to check but you want to check that the barrel the nozzle slides over is not cracked or damaged.

 

[cbrownfish]

LMAO! Seriously. I just walked in to pull the skimmers apart and swap the housing......what do I see? FOAM coming up the riser tube! I mean 4-5 days of NOTHING and now the first puff of foam is reaching the lid??????????? Maybe some slight imperfection in the nozzle connection was finally coated with bacteria/algae and it hit it's stride?

Insanity I tell you, insanity! I guess I will monitor the skimmate production and check the nozzle and housing assembly soon.

 

[rvitko]

It is always difficult with two skimmers, if they aren't almost perfectly matched, one will beat the other.

 

[cbrownfish]

Well, I cleaned the cups so I could monitor the non-performer. That was apparently too much and it went back to not skimming. I will try swapping housings and evaluate them.

PS: I have had the 2 runnning together successfully for quite some time. I agree that they are competing and it is unlikely that they will run in perfect harmony (one has always pulled a bit better). However, skimmer A is pulling half a cup in 24 hours......I would not expect skimmer B to be at zero.

 

[cbrownfish]

Ok, I swapped the pumps/housing about 2 hours ago. I actually took the pump from one skimmer and put it on the other skimmer. I left the housing in the skimmer that it was already in. Skimmer B is now pushing foam and Skimmer A is not. Skimmer B has generated several ml's of skimmate. Before starting the skimmers, I cleaned both cups and riser tubes so they started with clean surfaces, etc.

Could this be impeller related like the last? Could the plastic insert in impeller canal be warping slightly, resulting in less GPH and/or air intake? Or would a pump motor actually fail by slooooowing down somehow?

The repaired pump is labeled with 147 and the other is labeled with 238.

 

[rvitko]

The only possibilities are that the impellers are different or the venturi on one is not right.

 

[cbrownfish]

Let me clarify, as I realized that my terminology was a bit sloppy above. The motor that seems to get each skimmer to work effectively, marked with 147, has performed fine on both venturi's/hydrofoamers/nozzles and in both skimmer bodies. I should have said "I swapped motor blocks but left each hydrofoamer, nozzle and housing intact". So in effect, I ruled out out anything aside from the motor block, impeller, drive unit, bushing and o-ring (drive unit assembly looks like 7200.600?).....true?

Visually both impellers looked the same to me, the same drive unit with the same plastic bushing and small orange o-ring. Unless you have another suggestion, I will try putting both impellers side by side and look for subtle differences. I will also examine the canal that the drive unit goes into and see if there are any imperfections or warping (on 237 of course, since 147 has a new "canal").

***BTW, thank you so much for your assistance and attentiveness!! ***

 

[rvitko]

Those pumps would have been made only at most 2 months apart. I think that there is likely a difference in the impeller diameter, I would stack the impellers so you can compare them, one may be a couple mm bigger than the other. We were getting reports of pumps not starting in lower voltage conditions and the solution was to make the impeller 1.7mm smaller. This was more of an issue in Latin America where power frequently dips below 110V. If you have at least 117V you should be able to use the bigger impeller though the smaller one is the norm now.

 

[cbrownfish]

Well Roger, you certainly know your equipment and engineering intricacies. I pulled out both impellers and I did indeed find that one of the impellers was different than the other. One had nice rounded ends and the other had flatter/altered tip. The latter does look shorter by a smidge (1.7 mm I guess). Must be I did get one of the original stock impellers and one of the shortened stock impellers. Here is a picture with descriptions

I guess I will order the impeller off Tunze's website and get motor block 238 performing at a higher level! Do you know the part number offhand?

 

[rvitko]

Yes, but all of our stock is the new shorter one. It is part 0235.120. I know I have few used longer ones around, if you give me your address I will put one in the mail. Usually the shorter one works fine but the air flow needs to be open further, in fact the shorter one is closer to the European spec, the longer one makes the 60Hz version about 10% stronger than the European spec.

 

[cbrownfish]

Thanks so much Roger, PM sent!

 

[cbrownfish]

Hi Roger, I received the impeller in the mail....THANK YOU again! I installed it and note that both skimmers are now producing similar turbulence with the cups off. I expect to see improved skimming from the 238 pump.

That skimmer (238) did eventually start to work along side the one with the 147 pump. It was producing about 1/3 of the skimmate that 147 was. I will make a note as I see the results of the impeller change, just to make a record of the event.