Dust problem for third year running...

poolboyjohn

Member
Apr 17, 2020
9
France
Hi all,
I've been reading loads on the TFP forum and thought it was not only time to say "Hi" but also ask for some help as I'm clearly getting something wrong somewhere...
I setup my pool in 2018 so I'm in my third year. The pool is an 'above' ground pool of 8x4m using a saltwater treatment system. I'm located in France which sadly means some of the pool testing equipment you guys recommend isn't easily available out here...
Back to the problem then : I'm constantly having a "dirt" issue in the pool. It feels like dirt (not slimy) though it disappears when you touch it (very fine dusting).
I've been thinking its mustard algae from the beginning but apart from a slight brown/dirt colour, it is not at all a yellowish/brown and is all over the base of the pool with a main concentration in the center of the pool.
I've tried cleaning it (to waste) but the next day it looks identical, I've recently started putting some cleaning socks in the skimmer and they are coming out incredibly dirty...
Here are a few photos of the situation:
Photo 2.PNGPhoto 3.PNG
Photo 1.PNGPhoto 4.PNG

That being all said, I have just ordered a pool tester / photometer with PH, CYA, DPD 1 & DPD 3 tablets so I can test the PH, CYA, FC and CC.
I've also orderd the Taylor K-1515-A 21,26gm FAS-DPD kit.
Sadly because of the current global situation, I may be waiting a few weeks to get this all delivered.
As for my current readings, my pH is approx 7.2, I honestly can't read the chlorine colour so I'm saying its 0-0.5 (I've just upped the filtration time which means my electrosis machine is going to run for longer)
An idea of what my issue could be ? I'm looking forward to being able to accurately read the FC, CC & etc when I get the kit...
Best to all,
John.
 

kimkats

Mod Squad
LifeTime Supporter
Jul 10, 2012
47,054
Tallahassee, FL
That sure does look like sand/dirt but your siggy says glass filter...........Do you have a table outside by the pool? Does it get dirty fast? How about your cars out front?

Your FC is mighty low. You need to get it up and keep it. Look at this chart: FC/CYA Chart Letting it get low and staying low you are chancing an algae outbreak.
 

poolboyjohn

Member
Apr 17, 2020
9
France
Hi Kimkats,
Thanks for your response. We have a lot of dirt/pollen in the air at the moment (car is very dirty).
The dirt reappears overnight and honestly, the floor is really covered in the "dust".
Yes I have a "sand filter" but I loaded it with glass media as per the pool supplier's recommendations.
As for the FC, I've just increased my CYA as it was way too low... I'm going to do some more measurements later today once it has had time to dissolve.
I've also turned my SW machine to 100% to check all is ok...
 

Msch99

Gold Supporter
Bronze Supporter
Jun 11, 2018
906
Verona, MO
Our pool is partially under a tree and we also have a sand filter. “Dust”. “Something fluffy” would always collect along any creases in our liner. We used fine skimming nets to try and collect it but were only moderately successful

We bought a Dolphin robot last year which has helped tremendously.

Thinking that our sand filter wasn’t fine enough to filter out even if the stuff was suspended and made it to the filter.
 

cfiddes

New member
May 12, 2018
1
Chicago/Illinois
Hi. I'm having a very similar challenge. First year with this house and pool. Removed the cover on the pool 3 weeks ago to find a jet black swamp. Through SLAMing have returned the water to very high clarity, but now chasing the same problem as above. Very fine accumulations that persist despite SLAM chlorine levels. The accumulations are in various locations - In the deep end - at the bottom of the sloped side walls (ie. on the perimeter of the flat bottom) and in the shallow end on the vinyl liner seams and then in clumps with no clear pattern other than possibly where water flow from the jets is potentially pushing the algae or sediment.

Thought 1 - Algae was persisting despite maintaining high chlorine levels due to inadequate scrubbing. Currently committed to scrubbing the entire pool 2x per day.
Thought 2 - Dead algae accumulations - as the algae has been killed over the past few weeks it is still falling and accumulating on the bottom in which case this is just a patience game - let it precipitate out and vacuum it up. At high chlorine levels I'll win the game. The fact that the accumulations in teh deep end are at the bottom of the sloped slides supports the idea this is something falling and sliding down the walls accumulating primarily on the sides of the bottom.
Thought 3 - Not algae that is accumulating - dust or finer sand particles escaping the filter (broken "fingers" in the filter). The color is not "sandy" so this seems less likely. Going to put my 17 y/o to work emptying the filter after I order some new "fingers" for the filter.

PH - 7.4
FC - 22.5 (as of last night)
CC - zero to 0.5
TA - 150 (high but working it down - has been a challenge to get down fast with the refilling needed from vacuuming to waste.
CYA - 60 (had it ~30 while slamming, thought I was done so started bringing it up)
Pool is 25k gal

Returned to SLAM levels late yesterday ran the filter for 4-5 hours and then shut off filter overnight. Had noticeable accumulation overnight.

Any and all input welcome. I'm in search of the unicorn that is an algae free pool!

Thanks.
 

poolboyjohn

Member
Apr 17, 2020
9
France
Thanks for the extra posts guys, clearly I'm not on my own here...
I called the guy who did my whole SW system and he said that because I have a Redox electrode I must maintain my CYA at less than 15ppm, and that he said it was normal the FC levels are not measurable as the chlorine disappears instantly... hence why I need to do the majority of my filtration at night!
Does this make sense ? I've just made the mistake of adding CYA to bring it up to what you guys say but don't know if I've shot myself in the foot here...
 

Msch99

Gold Supporter
Bronze Supporter
Jun 11, 2018
906
Verona, MO
I strongly advise following TFP and the experts advice. Do not try to follow both pool store / builders advice and TFP. They don't mix well.

I do not know the system you are referring to, but FC doesn't disappear instantly. It is consumed by algae or UV source.
 

poolboyjohn

Member
Apr 17, 2020
9
France
Hi, I'm desperately waiting for the pool testing kit I've ordered to be able to have proper readings...
I've just been for a swim after a pool clean and noticed tiny black spots a bit everywhere on the floor of the pool which are really hard to remove (did come off when scratching with my nail)... could that be black algae ? I know that I have some copper in the pool following a pool treatment, could it be that ?
 

poolboyjohn

Member
Apr 17, 2020
9
France
Black algae usually only grows in plaster pools. If you can scrape off a sample and wipe it on a piece of white paper or index card, the smudge will be green. Read all about it here:

Hi Rancho,
It's hard to get off but I'm using a scrubbing pad and it is coming off - Its the size of a pin prick but there is quite a lot of them, all around the bottom edges of the pool... I would say from scratching (from the little i can see) that it is more orange colour than green... any thoughts? thanks
 

poolboyjohn

Member
Apr 17, 2020
9
France
Hi all,
Well I've got my test kit but can't get my hands on any bleach for now... waiting for another ten days or so for the stores to hopefully open back up!
My SWG is running at 80% but my FC levels seem to be stable at 1.5-2ppm.. I can run it higher at 100% but that is the "shock" level and cuts out back to 80% after 36 hours.
Basically, I cannot run my pool at the FC levels required using my SWG it seems (it's only 2 years old, is that normal I can't get that high with it?)...
On that basis, what do you recommend for me to do an OCLT test ? Do I turn off the SWG, test the chlorine level, then add bleach to get it above 3ppm, then measure 30 mins later to check ?
Trying to find a way round this. I keep getting this muck at the bottom of the pool and still wondering if it is pollen (we've had loads of pollen recently, cars are all covered in the stuff) but I read that pollen floats ?
If it is "gritty" to the touch (the stuff at the bottom of the pool) can it be live algae ? dead algae ? dirt ? a mixture of dead algae and dirt ?
Maybe I'm too difficult and it is normal to have this dirt at the bottom of the pool ?
Thanks in advance of yoru help guys, really appreciate you taking the time !
Best from france,
John.
 

Newdude

Well-known member
Jun 16, 2019
4,573
NY
. I keep getting this muck at the bottom of the pool and still wondering if it is pollen (we've had loads of pollen recently, cars are all covered in the stuff) but I read that pollen floats ?
If it is "gritty" to the touch (the stuff at the bottom of the pool) can it be live algae ? dead algae ? dirt ? a mixture of dead algae and dirt ?
If everything else is covered in pollen/dirt, so is the pool. Some of it floats to the skimmers, some of it sinks and makes cloudy water, while the rest sits on the bottom. You could always also have algae but the 2 don't have to happen at the same time.

here is how you Overnight Chlorine Loss Test and it will tell you if there is any algae with the pollen. The SWG needs to be off for the test

I would keep running the SWG at 100% to see if it made enough FC to keep your ideal range. With no chlorine available its your only option that doesnt add other chemicals like CYA or calcium..... if you cand find the other options too. Turning it back to 100% every day is less work than having to SLAM. (I would manually adjust it once a day on my schedule, and not wait for the 36 hours to expire in the middle of the night) And the difference between 80 and 100% on your SWG lifespan for a few weeks will be unnoticeable.