Spa flow decreases through the day

[BowserB]

Pool opened for the first time September 2018. Pool, spa, filter, O3, UV-C, SWCG, heater, then split to pool and spa. I normally have run the pump 8am to 8pm at 1600rmp with the divider valve set between the spa and pool returns so that the spa just barely trickles over the edge into the pool. You can see the position of the valve in the attached image at about the 10 o'clock position. You can see my most recent test results with the TFP test kit. I went out a couple days ago, around 6pm as I recall, and the spa spillover was dry. Pump was running. Skimmer socks were pretty clean, and water was flowing like it normally does. Water temp was 92; air temp 105. Looking at Pentair Home on my iPhone, I saw the usual 1600 rpm for the filter pump, but the water flow had dropped from the usual 20 to 17GPM.

There is a window into the spa backflow preventer that gives a bit of a view, although if there are no bubbles it's hard to see if there is moving water or not. I moved the lever to full flow to the pool and none to the spa. Then I switched it back. Water began to flow into the spa again. I reset the lever to the spa trickle over setting. For no reason other than wanting to do something, I increased the pump from 1600 to 1725rpm (half of full speed.) Every thing looked fine. Next morning 8am started up normally. By the end of the day, the spa spillover was almost stopped. Exercising the diverter got it working again. I'm a little reluctant to take that diverter apart, even though it seems like that might be where the problem is. My success rate with take apart ventures has not been very good in recent times, so before I risk taking the pool out of service, I wonder if any of you more knowledgeable than I would care to express an opinion. Thanks.

 

[ajw22]

Clean your filter.

Do a Overnight Chlorine Loss Test

 

[Jimrahbe]

Bill,

What you described is the first sigh of algae, even if you can't see it yet.

As Allen points out... you need to get your FC up between 5 and 10 ppm and then do an Overnight Chlorine Loss Test.. Or OCLT.

Thanks,

Jim R.

 

[BowserB]

Really? Filter was cleaned two months ago. FC almost never below 5ppm. CC not above -0- for three or more years.
So the algae is in the diverter? Huh?
OK, I asked, you answered. I will clean the filter and bump FC to 10ppm, then do an OCLT.
Bummer.
Thanks.

 

[ajw22]

Algae is in the water and clogs the filter. The diverter has nothing to do with it.

You can have algae with 0 CC.

 

[BowserB]

Algae is in the water and clogs the filter. The diverter has nothing to do with it.

You can have algae with 0 CC.

Not challenging your conclusion, but a question: Why would the effect increase through the day? Second question. I've kept FC at 5 or above except one time a few months ago when if fell to 4 after days of rain overflowing water into the street. Another thing. My wife had been dealing with a respiratory problem since mid May, so we've not even used the pool (so we're not the problem.) I'm going to do the OCLT tonight. We'll clean the filter tomorrow regardless of results. It's just that...well, algae! It's like the STD of swimming pools. How can we have algae? Is it the heat? We've had more record high temps this summer than I can remember ever. 100 used to be news. It still is, but now it means a cooler day. Water temps for the last month or more have hit 92 or 93 pretty much every day. Right now the air temp is 102 and the water temp 93. All other things being equal, is this why we're getting algae?
Will this be on our record now?

 

[ajw22]

Why would the effect increase through the day?

Your pump turns of at night? If so the dirt on the filter slumps off when the water flow stops and drops to the bottom of the filter. That cleans parts of the filter.

Over the course of the day the dirt and algae coats the filter and slows the flow until the pump stops.

And then the cycle repeats.

Second question. I've kept FC at 5 or above except one time a few months ago when if fell to 4 after days of rain overflowing water into the street. Another thing. My wife had been dealing with a respiratory problem since mid May, so we've not even used the pool (so we're not the problem.) I'm going to do the OCLT tonight. We'll clean the filter tomorrow regardless of results. It's just that...well, algae! It's like the STD of swimming pools. How can we have algae?

We don't know if it is algae or just a general dirty filter until you do the OCLT.

Is it the heat? We've had more record high temps this summer than I can remember ever. 100 used to be news. It still is, but now it means a cooler day. Water temps for the last month or more have hit 92 or 93 pretty much every day. Right now the air temp is 102 and the water temp 93. All other things being equal, is this why we're getting algae?
Will this be on our record now?

Report on the OCLT results and clean the filter and we can discuss more.

 

[Jimrahbe]

Bill,

Algae is the most likely cause... So, if for no other reason, you need to eliminate it as the problem...

I assume that you turn your pump off at night and that you run it during the day. When you turn the pump off, some of the dirt/dead algae in the filter can fall off and drop into the bottom of the filter. As the day goes on the filter gets dirty again.

But.. I am open to other ideas.. What else can cause poor water flow that increases during the day???

Thanks,

Jim R.

 

[BowserB]

Bill,

Algae is the most likely cause... So, if for no other reason, you need to eliminate it as the problem...

I assume that you turn your pump off at night and that you run it during the day. When you turn the pump off, some of the dirt/dead algae in the filter can fall off and drop into the bottom of the filter. As the day goes on the filter gets dirty again.

But.. I am open to other ideas.. What else can cause poor water flow that increases during the day???

Thanks,

Jim R.

Jim, you're in Texas. We're in Katy just west of Houston. Would our recent weeks and weeks of 100+ degrees be a factor here? I mean if 5-6ppm prevents algae for 4.5 years, and then it doesn't, is temperature the new variable that matters? Again, with my wife's respiratory problem we just haven't used the pool this summer. I haven't slacked off maintenance though. I err on the high side for free chlorine. What do you think? My wife is so upset at the thought of algae, she wants to sell the house and move to Portugal!

 

[wdsheffer]

Bill,
If you do SLAM, and don't know about Patriot Cleaning Supplies, check it out. You'll need a lot of liquid chlorine. He's at Mason and Morton and sells LC for $3/gallon (12.5%). Bring your own container. He has a dispenser for gallon jugs if that's what you've got. (That's what I've got.)
Houston Bleach and Liquid Chlorine Distributor – Katy, TX Pool Shock Wholesaler for Bulk Sodium Hypochlorite

 

[Jimrahbe]

Bill,

I hear it is nice in Portugal this time of year..

I think before you move, that you need to do the OCLT and see where you are.. Make sure the cell is off and that you start with an FC of between 5 and 10 ppm.

Everyone seems to have an excuse as to why they have algae.. it is the rain, or it is the heat, or ????? All these things might make a slight difference, but they are not the real reason.. I see two likely scenarios...

1. You original did a SLAM, but killed most the algae, but not all of it.
2. You let your FC drop too low compared to your CYA level

Once algae is in the pool... keeping your FC at the target range will not kill all the algae. It might knock it back for a while, but it is still there.

Obviously, there is no way I can know if you actually have algae or not via the internet... I 'assume' you do based on your description of the problem. It just makes sense to do the OCLT first to see where we are.

How old are your cartridges? Have you used any kind of Floc or other pool store magic?

Assuming you pass the OCLT, and don't move to Portugal, then I suggest that you remove the cartridges and run for a day and see if you still have the problem.. Assuming the problem goes away, I'd replace the cartridges and see what happens.

Thanks,

Jim R.

 

[BowserB]

Thanks, WDSHEFFER for the chlorine seller. I will check that out. Very conveniently located. We're just north of Franz at Avenue D in Katy. Good price, too. I just dropped a gallon container in the recycle bin. I'll retrieve it asap.
Jim, I've never needed a SLAM in our five years with this pool--unless I need one now, that is. Cartridges are the originals, so they're five years old. Haven't used any magic potions on them. Simple Green a couple times. Last cleaning two months ago, they looked pretty good. Of course, I've never believed you could really clean those things from the outside. Seems like high pressure from inside would be necessary. This time I may spray them with straight 10% chlorine--or maybe 12.5% from Patriot Cleaning Supply.
Thanks to both you guys.
Bill

 

[BowserB]

OK, Jim and WDS. I poured the last of a container of 10% Walmart pool chlorine. SWCG off, pump continued running another 2+ hours later, I was ready for the OCLT. Got my evening sample. FC=7.5ppm. This morning at 7:30 I ran the pump for 10 minutes and got a new sample. FC=7.0. Down 0.5ppm. According to TFP, 1ppm or less means no organic contamination. However, I still poured my last unopened Walmart chlorine into the pool (thanks again, WDS, I'm taking three empty 1-gallon jugs to Patriot Cleaning Supply tomorrow.) I'm going to clean the filter cartridges this afternoon and carefully check the bottom of the tank before I open the drain to flush it. I'll also run another OCLT tonight.

 

[mknauss]

Great! When you can clean the filter, I would try running the system with out the cartridges in the filter housing. Just another check to rule out any plumbing/valve issues.

 

[BowserB]

Great! When you can clean the filter, I would try running the system with out the cartridges in the filter housing. Just another check to rule out any plumbing/valve issues.

Thanks, Marty. I think I recall from your reply to someone asking the useful life of a filter cartridge, that you were on something like year 7 for your cartridges. Still doing OK?
Incidentally, I have one end of my cartridges marked so that each time I clean them, I flip upside down. Good idea? Bad idea? I do it because it seems that the only place I can see debris is about the bottom third of the cartridge, and this seems a way to even out the wear.

 

[mknauss]

I replaced mine late last year after 8 years. The fabric had started to fray in spots.

Not sure about the flip end to end. Not sure it will hurt. My cartridges are uniformly dirty when I clean them each year.

 

[wdsheffer]

(thanks again, WDS, I'm taking three empty 1-gallon jugs to Patriot Cleaning Supply tomorrow.)

Cool, just note that he’s 8am-noon, Mon-Sat. So don’t expect to swing by after work. He answers texts at the number on the website if you have any questions.

 

[Jimrahbe]

Got my evening sample. FC=7.5ppm. This morning at 7:30 I ran the pump for 10 minutes and got a new sample. FC=7.0. Down 0.5ppm

B,

That is good news and that is bad news..

It is great you don't seem to have algae, but it is bad, as now what???

I can't think of anything else that would directly cause your problem.

As Marty points out... Maybe a cartridge issue.

I replace my original cartridges after about 8 years as I just got antsy... I could not tell any difference between my old ones and my new ones.

Since you have an unusual issue, I'd start with new cartridges. I'd run with the cartridges removed, for a day or so, and see of the reduced flow issue is still there first.

Please let us know what you find as it might help others with the same issue,

Thanks,

Jim R.

 

[BowserB]

Guys, thanks again for sticking with me on this. Update. I cleaned the filter. Anyone remember in the weather reports about the Sahara dust in the atmosphere. I had almost forgotten that every time I've run the Dolphin, the two collection bins end up with mud in the bottom. When I opened up the filter, there was that same mud in the bottom of the filter can. Also as I ran my hose back and forth across the face of the cartridges, I saw a white streak in the brown--and that was top to bottom on all four cartridges, with a bit more toward the bottoms. There was so much obvious mud that I didn't even bother trying the system with no cartridges. At 1825rpm before the cleaning, Pentair Home was reporting water flow of 26 GPM. After cleaning, 31 GPM. Right now I'm showing 9ppm FC and pH of 7.4 with the IC-40 set on 100% (normally it's on 40 or 60 depending on whether I need to to fall or rise a bit.) I'll run an OCLT tonight.

WDS, thanks for the heads up on Patriot Cleaning Supply hours. I'll get by there Monday morning. Even with the SWCG, I like to have a couple gallons of chlorine on hand. Never know when another pandemic will pop up--next year being an election year and all. I'm going to stock up on toilet paper too!

 

[Jimrahbe]

Bill,

Sounds like you found it..

Please tell me your normal schedule for running your pump?

Just trying to fully understand the issue.

Thanks,

Jim R.