Sand filter clogged by flocculant/clarifier?

[Torrente]

I am starting to think that my Pentair Tagelus TA-100D sand filter might be clogged, the reason because I think of it is because I have to backwash it every time that I vac the pool. Pool is not dirty but coinciding with a big overhaul 2 months ago I regrouted the gap between tiles and I can see that dust color coming out when I brush the pool.


Sand is only 2 years old but following pool store directions I had used flocculant through the filter and clarifier, this was before I knew of TFPC and I have learned that it was a mistake.


These are some numbers of the filter measured with a flow meter and TFTestkits gauge:

• Regular pump working: Intelliflow at 1300RPM, filter “clean” measured 25GPM, filter at 5PSI
• High flow for cleaning pump working: Intelliflow at 3000RPM, filter “clean” measured 75GPM, filter at 19PSI. After vac: 35GPM, filter at 33PSI, I need to backwash around 1 minute to get quite clean water.

How does this looks? Can I do anything more to diagnose it?


The possibility of changing the sand is there but I would prefer not to do it, the chemical cleaning product that I have available in Panama is HTH filter cleaner. Does it worth to make a try of using that product and a deep cleaning?


Thank you!

 

[Catanzaro]

Torrente:

My first question would be to look at your skimmer(s) for flow and also place your hand in front of a return eyeball. Are you feeling descent pressure? If so, then this could be totally normal.

Q: Regarding the numbers, what is your regular pressure at high speed after backwashing?
Q: After back washing, how does the pressure feel with your hand over the eyeball return?
Q: How long after (approximate) do you need to backwash and how much does the pressure rise?

This will help you determine if this are working properly. IMO, the pressure of 19 could be totally normal. I do not have a VS, so not familiar with low speeds. My PSI is at 21 because of the backpressure of the rotating heads.

Q: What exactly is the issue? Algae, cloudy water, floating particles, etc.? You also may want to try a DE alternative. I just used Fiber Clear which may not be available there and by tomorrow I will know if the pressure has risen and the difference in the water clarity.

 

[niteshift38]

I made the same mistake once and let flocculant run through my filter sand . I tried the cleaner and "deep cleaning" the filter and still had similar results as you (having to backwash almost daily). I replaced my sand as a last ditch effort and that solved the daily backwash issue. Maybe there is another alternative out there, but I didn't find it.

P.S. I've used the filter cleaner on occasion when I suspected my sand was getting "channeled", but follow directions precisely, I am able to shake my tank frequently while it's working and then backwashed (sending chemical to waste), and rinse as normal.

Good Luck!!!

 

[Torrente]

Thank you for your answer.

My first question would be to look at your skimmer(s) for flow and also place your hand in front of a return eyeball. Are you feeling descent pressure? If so, then this could be totally normal.

I do not have regular skimmers as pool is infinity, in the returns I feel normal pressure

Q: Regarding the numbers, what is your regular pressure at high speed after backwashing?

Intelliflow at 3000RPM, filter “clean” measured 75GPM, filter at 19PSI

Q: After back washing, how does the pressure feel with your hand over the eyeball return?

Normal

Q: How long after (approximate) do you need to backwash and how much does the pressure rise?

We vac 2 times per week and I have to backwash every time that I vac. After vac: 35GPM, filter at 33PSI

Q: What exactly is the issue? Algae, cloudy water, floating particles, etc.? You also may want to try a DE alternative. I just used Fiber Clear which may not be available there and by tomorrow I will know if the pressure has risen and the difference in the water clarity.

I do not have another issue as far as I know, water is clear, FC use is normal, no CC. OCLT is fine. Water just get a bit cloudy after brushing the pool (I brush it once per week)

- - - Updated - - -

I made the same mistake once and let flocculant run through my filter sand . I tried the cleaner and "deep cleaning" the filter and still had similar results as you (having to backwash almost daily). I replaced my sand as a last ditch effort and that solved the daily backwash issue. Maybe there is another alternative out there, but I didn't find it.

Thank you for your answer, it helps to know it.

 

[Catanzaro]

What concerns me a little is that normal pressure is 19 PSI, vacuuming and pressure increases to 33 PSI. This is a huge jump and if the water is clear, I can not imagine how you pressure can increase this much. Before vacuuming, is your water clear? Can you fill the walls to see if they are clean? Backwashing every time you vacuum or weekly will not keep the water at the same clarity. Sand filters work better when filter is slightly dirty.

Are you sure your pressure gauge is functional? Assuming you have a lot of trees that may drop stuff in the pool.

 

[Torrente]

Are you sure your pressure gauge is functional?

Gauge should be ok, it is new as I changed it 2 weeks ago because I did not trusted the previous one, but the data while the new one has better resolution is the same.

Assuming you have a lot of trees that may drop stuff in the pool.

I have some trees but I do not use to have a lot of stuff from them

This is the information from today’s vac:

Before starting to vac pump at 3000RPM, filter “clean” water flow 73GPM, filter at 17PSI.
Photo before:

After vac pump at 3000RPM, water flow 35GPM, filter at 30PSI.

After backwash for 1.1 minutes: pump at 3000RPM, water flow 75GPM, filter at 17PSI.
Photo after:

 

[Catanzaro]

I am wondering if you have dead spots in the pool, due to circulation and then as you vacuum, brush, pressure increases and backwash, you eliminate the bad stuff and then start all over. The only disadvantage to this is the loss of chemicals (mainly CYA), and possibly other chemicals. Let alone the water replacement. Water looks good, it is just strange that a 13 PSI increase happens during vacuuming. Do you place the valves back to normal and remove the vacuum, plate, etc. before looking at the pressure? Your pressure will change based on a change in configuration.

 

[Torrente]

I am wondering if you have dead spots in the pool, due to circulation and then as you vacuum, brush, pressure increases and backwash, you eliminate the bad stuff and then start all over. The only disadvantage to this is the loss of chemicals (mainly CYA), and possibly other chemicals. Let alone the water replacement. Water looks good, it is just strange that a 13 PSI increase happens during vacuuming. Do you place the valves back to normal and remove the vacuum, plate, etc. before looking at the pressure? Your pressure will change based on a change in configuration.

Thank you for your answer, in my understanding everything is correct, what would be the symptoms of a clogged filter by flocculant/clarifier?

 

[Torrente]

Curiously I thought that I had the Sand Dollar 80 but it seems that I have the Tagelus 100D, one thing that I am pretty sure is that the filter is loaded only with 350lb of sand while it supposed to have 600lb… probably this explains the estrange behavior, coinciding that I would have to put more sand I will waste te current sand and start new.

 

[Catanzaro]

Thank you for your answer, in my understanding everything is correct, what would be the symptoms of a clogged filter by flocculant/clarifier?

This is possibly the reason for such a high increase in pressure all of a sudden. It may be time for sand change due to the clarifier. Unless you want to take apart and remove the top layer if all gummed up, but you will only know by doing a little bit of investigative work.

 

[Torrente]

[FONT=&quot][FONT=&quot]Hello, first of all thank you for all the answers.[/FONT][/FONT]
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[FONT=&quot][FONT=&quot]Just an update of the situation to close the incident.[/FONT][/FONT]
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[FONT=&quot][FONT=&quot]Instead of just adding the needed sand to get to the product recommendations and to avoid any future doubt about the potential clogging caused by the floculant, I have replaced all the sand to the prescribed amount. After this it seems to work normally.[/FONT][/FONT]
[FONT=&quot][FONT=&quot][/FONT]
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[FONT=&quot][FONT=&quot]These are the current figures of the filter measured with a flow meter and TFTestkits gauge:
[/FONT][FONT=&quot]- Regular pump working: Intelliflow at 1300RPM, filter “clean” measured 22GPM, filter at 4.5PSI[/FONT][/FONT]
[FONT=&quot][FONT=&quot]- High flow for cleaning pump working: Intelliflow at 3000RPM, filter “clean” measured 62GPM, filter at 13.5PSI. After vacuum: flow around the same, filter 14PSI[/FONT][/FONT]

 

[jblizzle]

Now backwash when the pressure rises 20-25% over the clean pressure.
Check is best done at the higher speed.
With a clean of 13.5psi, backwash at 16.5psi, 17 at the latest.