Losing flow

[pouyan_afshin]

Good evening:

When I open up the filter and clean it up, and rerun the pump I have a very nice flow of water sucking the water from the pool and push it to spa which falls back to the pool. However, usually after 2-3 weeks I see significant drop in flow of water. The filter pressure after cleaning is 15 psi, and the flow is around 35 (I have a flow meter) when I see the slow down it is has just become 16 or so, and flow is 25 and I usually see half the pump basket does not have water anymore. Any idea what can cause the pressure to drop down that significantly. I am using a 60 cubic feet DE filter, and I am just adding acid, chlorine and baking soda to the pool.

Thanks

 

[mknauss]

Welcome to the forum!
That is typically the sign of algae in a pool. Though 2-3 weeks to clog up means you are just barely holding it back.
How are you testing your pool water chemistry?
I suggest you read ABC's of Pool Water Chemistry.

 

[pouyan_afshin]

Welcome to the forum!
That is typically the sign of algae in a pool. Though 2-3 weeks to clog up means you are just barely holding it back.
How are you testing your pool water chemistry?
I suggest you read ABC's of Pool Water Chemistry.

Thanks mknauss for your comment. There is no algae in the pool. The water is all clear blue. There might be very little green spots once in a while. Are you saying those little green spots can clog the filter?

 

[mknauss]

If you have any visible algae, your pool water is full of algal spores.
You need to follow the SLAM Process. To do that, you need a proper test kit, see Test Kits Compared. I suggest the TF-100 A proper test kit is needed to get the accurate water chemistry results needed to follow the TFP protocols.

 

[Richard320]

I agree with Marty. That's textbook algae. You're in a stalemate. You've been keeping the chlorine high enough to kill it at the same speed it's growing. So you have an endless supply of dead algae carcasses to filter out. Once in a while for whatever reason, you get behind, and you actually see algae spots. If you ignored it, in a couple days your whole pool would be green. When it clogs up the filter, you backwash it away, and the cycle repeats.

 

[pouyan_afshin]

I agree with Marty. That's textbook algae. You're in a stalemate. You've been keeping the chlorine high enough to kill it at the same speed it's growing. So you have an endless supply of dead algae carcasses to filter out. Once in a while for whatever reason, you get behind, and you actually see algae spots. If you ignored it, in a couple days your whole pool would be green. When it clogs up the filter, you backwash it away, and the cycle repeats.

Thank you Richard and Marty. That was a great analysis. I actually keep the Chlorine level between 1-3 all the time, and Cyanuric acid is at 30. I see these spots, shock, and see it back after a few weeks. I read in TF0 just a few min ago that I need to raise Chlorine to 4-6? I thought it might be slightly hatmful for skin if it goes higher than 3. Would you please advise?

 

[mknauss]

Follow the FC/CYA Levels. You can swim safely in a pool with FC up to SLAM level which is 40% of CYA level.

The 1-3 ppm FC stated by pool stores and chemical companies is old science. It does not take into account the effect of CYA.

If you wish to dive into the chemistry, see Pool Water Chemistry

 

[Richard320]

Thank you Richard and Marty. That was a great analysis. I actually keep the Chlorine level between 1-3 all the time, and Cyanuric acid is at 30. I see these spots, shock, and see it back after a few weeks. I read in TF0 just a few min ago that I need to raise Chlorine to 4-6? I thought it might be slightly hatmful for skin if it goes higher than 3. Would you please advise?

Nope, not going to melt your skin off. Your tap water could be higher.

What are safe levels of chlorine in drinking water?
Chlorine levels up to 4 milligrams per liter (mg/L or 4 parts per million (ppm) are considered safe in drinking water. At this level, no harmful health effects are likely to occur.

Disinfection with Chlorine | Public Water Systems | Drinking Water | Healthy Water | CDC

Education and information about water treatment, community water treatment, water systems, public drinking water, safe drinking water, coagulation, flocculation, sedimentation, filtration, disinfection, community water fluoridation, fluoridation, consumer confidence reports, CCR, household water...

www.cdc.gov

Then you add the buffering effect -- think buffered aspirin -- of the CYA. My first season I was stuck with astronomical CYA so I maintained FC up in the 20s and swam in it all the time. No red eyes. No bleached swimsuits.

Disregard the old pool store standards. They're designed to sell you more products.

 

[pouyan_afshin]

Nope, not going to melt your skin off. Your tap water could be higher.





Then you add the buffering effect -- think buffered aspirin -- of the CYA. My first season I was stuck with astronomical CYA so I maintained FC up in the 20s and swam in it all the time. No red eyes. No bleached swimsuits.

Disregard the old pool store standards. They're designed to sell you more products.

Thanks a lot Richard for your detailed answer, very helpful. I will try it out.

 

[pouyan_afshin]

Follow the FC/CYA Levels. You can swim safely in a pool with FC up to SLAM level which is 40% of CYA level.

The 1-3 ppm FC stated by pool stores and chemical companies is old science. It does not take into account the effect of CYA.

If you wish to dive into the chemistry, see Pool Water Chemistry

Thanks a lot for all the information. I will try it out.