New suction vac not sucking!

[Striving]

Hello,

I have a new Zodiac G3 Pro suction vacuum. I installed it according to the instructions. It moves a bit and then gets stuck in corners. It does not climb the walls, as it is advertised to do. It replaces an older Hayward Dolphin, which also limped around and needed a rebuild. One of the neat things about the Zodiac is it comes with a little pressure gauge to test the suction. They recommend a suction (based on their gauge) of 3 on a scale of 0-6. Mine is reading at the skimmer is zero, so it is insufficient, to say the least. However, there is suction, and it feels strong to my fingers (almost snaps them).

I checked the suction side water lines and detected no leaks. There are no bubbles at the pump or the SWG. The pressure at the filter is 22 psi, about what it has always been.

At the pump, my pumping only has two in-pipes (suction side) and two out-pipes. The in-pipe sources are the pool and the spa, as are the out-pipes. They can also be set as mixed (both spa and pool). I have the in-pipe source set as pool only.

The pool in-pipes come from two sources, including the drain at the bottom and the skimmer. I can't see any way of setting the in-source as skimmer only.

Does anyone have suggestions for increasing my suction at the skimmer? Also, is it possible, my pool wasn't designed for strong suction, and, therefore, a suction vacuum?

BTW, I am a newish pool owner. I bought this home last summer, and I'm gradually upgrading many years of deferred maintenance. Therefore, I'm definitely still learning the details of how the system works and ways of improving its functioning.

Thank you! Greg

 

[Texas Splash]

Good morning Greg. If it were me, I think I would try a couple things first:
1 - Clean the filter to make sure there is no excessive restriction slowing down your water flow. The gauge may/may not be as accurate as you think.
2 - I would experiment with the suction valves. You say you don't see a way to pull from the skimmer only? Maybe post some pics of your valves and the equipment pad. It may help us.

 

[Striving]

Good morning, Pat. Thank you for your feedback. I have experimented with the values, trying all possible position combinations of positions, but I'm not finding any position with adequate suction for the Zodiac vacuum.

I attached several pictures of the system, valves, and gauge readings. The first picture shows the only two plumbing values I have. As described in my original post, there are two in-pipes (suction side) and two out-pipes. The in-pipe sources are the pool and the spa, as are the out-pipes. The pool in-pipes come from two sources, including the drain at the bottom of the pool and the skimmer. I can't see any way of setting the in-source as skimmer only. If that was possible, presumably, it would increase the suction force at the skimmer.

The second picture shows the suction gauge at the skimmer. I tested it there to rule out leakage in the vacuum hose. Zodiac recommends "3" on that gauge. I'm getting zero (this is difficult to see in the picture, but the yellow piece is where the suction is measured). As I mentioned in my OP, that's a new piece of equipment that came with the Zodiac. Since I've owned this pool (less than a year), I don't think the suction force has noticeably changed. It was always a bit weak for my previous vacuum (Hayward Dolphin--which worked but moved slowly, which suggests low suction).

The final two pictures are the pressure gauges on my filter. The first is with the pump on and the second with it off. My pump is a Pentax FNS DE 48. The pressure gauge shows the recommended range. However, as Pat mentioned, the reading could be inaccurate. Note that I backwashed the system one month ago and added new DE. After the backwash, the pressure read 22, just as it does now.

One last thing I should mention is that I added a saltwater generator recently, but that did not change the suction noticeably.

I would love to have suggestions on how I might improve the suction, or if my system is not designed to provide the level of suction needed for a typical suction vacuum.

Thank you, Greg

 

[Texas Splash]

You may be at a disadvantage here. I have a Barracuda cleaner that came with that same vacuum gauge to detect water force (pull). It needs to be quite strong to provide adequate movement to the cleaner. In my case, I had to have my 2-speed motor (2 HP) on high speed. Low didn't work at all. So here I see in your signature that you have a 1 HP pump and it has to pull water from two locations. Based on those two factors you may continue to have trouble getting the Zodiac to respond as desired.

 

[Striving]

Hi Pat, I think this is the best explanation. I'm not knowledgeable about the correspondence of pump HP vs suction force. Are you aware of information on that?

Since my last post, I did a "minor backwash" (i.e., 20-30 seconds), to see whether too much DE or other filter cloggage may be the issue. This minor backwash reduced the filter pressure from 22.5 to 21.5, but still, the suction force at the skimmer was zero.

I also tried to clean the pump impeller using guidance from this video

. I did not detect any debris using this method (I could also stick my hand in for better detection).

I will try to contact Zodiac to see if a 1.0 HP pump typically provides adequate suction.

Greg

 

[Texas Splash]

You can certainly check the impeller. Be sure the power is OFF to the pump. You can reach down into the pump basket area with your fingertips to see if the impeller turns freely. If there is any debris lodged in the impeller you might not be able to tell unless you disassemble the pump.

The only other thing I could think of checking is your water chemistry to be sure you have no excessive organics which could easily clog up a DE filter. You won't even see the stuff. If in doubt, use your TF-100 or Taylor K-2006C test kit to run an Overnight Chlorine Loss Test. If you pass the OCLT, organics/algae shouldn't be an issue. But if you fail the OCLT, you would need to do a SLAM Process until completion which kills algae. Once all the dead algae is filtered out, filter pressure should be stable and perhaps a bit lower. So that's something to consider.

 

[Striving]

Thank you for these suggestions. I hadn't heard of the OCLT but will try it.

BTW, my water was immaculate all winter, but over the past month, I noticed some "fluffy" algae (i.e., dislodges with the slightest current or force) gathering on the walls despite FC in the 6-9 ppm range. That coincided with the local spring bloom, increases in water temperature (from about 55 to 75), and the addition of 400 pounds of salt for the new SWG. So, there may be a pollen/organics issue. However, wouldn't the backwash correct organics accumulation at the filter?

 

[Texas Splash]

However, wouldn't the backwash correct organics accumulation at the filter?

Unfortunately, only for a few minutes. You backwash and then 30 minutes later the filter seems clogged again. The fact you saw algae beginning to grow means there is a heavy demand on your DE filter. As you probably know, DE filters are notorious for filtering the fine stuff. The downside is they fill-up very fast with organic materials suspended in the water when algae is present.

So before you give up on the Zodiac, I would recommend the SLAM Process. Follow that page closely for best results. Once you pass all 3 SLAM criteria, your water should be much cleaner with less of a demand on the filter and hopefully more efficient water flow (suction).

 

[Striving]

Thank you for this recommendation. I will do an OCLT test and proceed to SLAM if the results show elevated organics. However, right now, the water is clear, and there is no algae. The build-up I reported was after a week or so of no brushing or vacuuming. So, at this point, I'm not convinced the water needs SLAMing. Still very open to correcting flaws in my understanding.

 

[Texas Splash]

So, at this point, I'm not convinced the water needs SLAMing. Still very open to correcting flaws in my understanding.

Very good. Let us know if you have any questions along the way. Good luck!

 

[Striving]

Just an update from yesterday.

I just completed the OCLT, and there was zero loss (6.3 ppm at 8 pm and the same at 7 am). I'm not surprised b/c I have not had to add much chlorine. That is mostly due to the fact that I have a pool cover ("solar blanket"). So, while there is not likely an organics issue with my water that is clogging my filter, that does not rule out some type of blockage at the filter. The comments after this video on suction repeatedly recommend not only hosing off the grid, both also giving them an overnight acid bath to remove grease and oil buildup that is expected to accumulate annually. While that buildup is possible, I doubt it's the issue with lack of suction b/c the filter pressure has been highly stable, and there have been few swimming in my pool, none with sunscreen, and all who showered first. How to Correct Low Water Pressure in Your Pool System - INYOPools.com

Also, I do not see any air bubbles in the pump basin, as described in this video.

That suggests there is not likely a suction-side air leak.

Circling back to the impeller blockage checking method I provided a video of yesterday, in retrospect, it is a very superficial approach, as any blockage will not likely protrude in front of the impeller in a way that it can be detected and removed by sticking a screwdriver in there. I'm hesitant to do a thorough job of inspecting the impeller b/c that will require removing and dismantling the pump -- a real pain and, therefore, a last resort.

There could also be some blockage in the pipes from the skimmer to the pump. although I'm not sure how probable that is or how it would be tested or corrected.

I have emailed Zodiac regarding whether my pump's HP may be the issue. Recall that my pump is 1.0 HP. Some web pages recommend higher than that for generating good suction, but I believe it depends on the system. My pump is about 17 feet from the skimmer, which I think is relatively close (good for suction). The copper pipes from the skimmer to the pump are narrow at 1.5 inches. That seems to suggest that the pump is expected to draw about 43 gallons per minute if working right. I do not have the equation for computing the expected suction force of my system or whether it is sufficient for the Zodiac G3 Pro vac, but I hope Zodiac can determine whether the pump HP is potentially the issue.

I'll continue to post on this in case it helps others resolve similar suction-side issues. Please reply if you have any suggestions!

Thank you, Pat, for all your helpful suggestions.

 

[Texas Splash]

Good you passed the OLCT. As for filter cleaning, acid baths are not something that "has" to be done on a recurring basis if the grids are cleaned periodically throughout the year. But if you ever do decide to do an acid wash, be sure the grids are 100% thoroughly cleaned with a good powdered dishwasher soap or TFP solution for a few hours and rinsed really well before using acid. Any residual material left on the grids has the potential to fuse permanently to the grids which would be a bad thing. Have a good day.

 

[Oly]

I'm guessing your primary issue is the limited power of your 1 hp pump and the inability to isolate only the suction line attached to your suction side cleaner and close the bottom drain line. Some skimmer box designs include access to the bottom drain pipe and allow an adjustment to control the skimmer vs bottom drain suction. Hard to tell from your picture if you have this option.

 

[Striving]

Hey Pat,

Thanks for this tip. I will hold off on the acid wash for now.

Greg

 

[Striving]

I'm guessing your primary issue is the limited power of your 1 hp pump and the inability to isolate only the suction line attached to your suction side cleaner and close the bottom drain line. Some skimmer box designs include access to the bottom drain pipe and allow an adjustment to control the skimmer vs bottom drain suction. Hard to tell from your picture if you have this option.

Thank you...I suspect you are correct.

At your suggestion, I just took a closer look at the skimmer box after removing the vacuum connector shown in my picture. I cannot see any valve. The copper pipe goes directly down, I suspect, eventually to the main drain. I also see a pipe connected to the downward pipe, about 3 inches below the skimmer box, that is horizontal and heading in the direction of the pump. That is likely where the main drain and skimmer lines converge. Again, no valve is there.

I also played with the "in-valve" (suction side) just before the pump, which I provided a picture of. Even when that valve is set for spa only, there is still some suction at the skimmer box. That suggests the valve is leaking inside. When I set it for the pool only, the suction does markedly increase (as expected). That is the original solid copper valve (44 years old). I replaced the upper valve (pressure side) last week ($75). The new valve is made of plastic, and I'm not convinced it improved anything. I'm not sure whether replacing the lower one will make a difference, or is advisable.

The company that constructed my pool is local and still in business. I may give them a call about their design, suction issue, and recommended pump HP. They may have a better sense of that than even Zodiac.

Thank you

 

[Oly]

Check out this old thread ...

Flow Restrictors Below Skimmer Basket?

There's, what appears to be, two adjustable flow restrictors residing below the skimmer basket. One is mounted on the under side of a removable plate and sits on the bottom of the skimmer box. It also appears to have a float valve in it presumably to block off the skimmer if the water level...

www.troublefreepool.com

 

[wireform]

So here it goes. Your in to the pump has pool or spa and you closed off the spa so now you have maximum pull from the skimmer. If the skimmer has two ports at the bottom which are open the the main drain (MD) pulls from the skimmer via an adjustable gizmo but if there's one port only or the second port is permanently plugged then we know the MD has a direct run to it with no way to close it as the "P" pipe would run to both. One way to temporarily close off the MD would be via the deep end by covering up the drain grate with a thick piece of plastic such as from a tarp making it a little over sized and laying it down there to stop the suction from there thereby increasing the skimmer to its max.

 

[Striving]

Check out this old thread ...

Flow Restrictors Below Skimmer Basket?

There's, what appears to be, two adjustable flow restrictors residing below the skimmer basket. One is mounted on the under side of a removable plate and sits on the bottom of the skimmer box. It also appears to have a float valve in it presumably to block off the skimmer if the water level...

www.troublefreepool.com

Thank you...I checked it out.

 

[Striving]

So here it goes. Your in to the pump has pool or spa and you closed off the spa so now you have maximum pull from the skimmer. If the skimmer has two ports at the bottom which are open the the main drain (MD) pulls from the skimmer via an adjustable gizmo but if there's one port only or the second port is permanently plugged then we know the MD has a direct run to it with no way to close it as the "P" pipe would run to both. One way to temporarily close off the MD would be via the deep end by covering up the drain grate with a thick piece of plastic such as from a tarp making it a little over sized and laying it down there to stop the suction from there thereby increasing the skimmer to its max.

Thank you for this. Plugging the main drain might be my best option.

I called the company that constructed the pool, and they still have my 44-year-old pool on file. They verified my observations (with considerable help from posters here). I have one skimmer and a main drain. They converge to a single pipe just beneath the skimmer.

I'm attaching a picture of the bottom of my skimmer. It's easy to see the 1.5-inch copper pipe going down and eventually to the main drain. If you look carefully, you'll also see a pipe coming in from the side of the downpipe, just a few inches from the skimmer bottom. That goes to the pump. All the suction is from that side pipe. The pool maker said that I could stick a plug below the side pipe and block the main drain "semi-permanently," and that would increase the suction. I don't know what kind of plug that would be, but he said they don't do that and to see a pool repair person. I suspect it's some kind of inflatable plug, b/c, otherwise, the suction would dislodge it. I asked if I could plug the main drain at the bottom, and he seemed to believe that method was not as good. I have no way of judging the quality of this suggestion.

He also said that a pressure-side vacuum is another solution. I looked at the return line at the pool entry, and there is no thread there, so I'm not sure how a vacuum would be connected (it seems most pressure vacs have a screw-in connection at the return pipe). I would love to hear what people recommend, given my plumbing.

I'll follow up again as I resolve this, in case it is helpful to anyone.

Thank you all!!

 

[wireform]

Thanks for the update. I still believe that my method will work equally well and a lot simpler. Prepare little bit of an over sized thicker tarp material or thin rubber mat while the pump is running and it'll seal it by virtue of suction.