bizare algae problem

[Aquaclear-NZ]

Right - im stumped, for the first time in 12 years of supplying algae treatments i thought i had seen it all, and somewhere in the back of my little mind i think i have seen this before.

its a white large flakey, almost calcium looking algae
originally i lent towards the SWG and possible build up on the cell, but client has already gone this way and removed it from the system, yet the flakes still appear

water balance is about right

cya 50
unsure on chlorine - but read on
ALK 100
CH 200 odd

bear in mind this customer is about an hours flight from home, so some info is a little bit second hand

whats lending me towards the algae theory is that the customer shocked the pool one evening with enough chlorine to theoretically get their FC level up to 8 - 9 ppm, by morning there was none left

these flakes seem to settle much like a mustard overnight

any theories will be most welcome - am currently running them through an aggressive liquid chlorine mustard treatment

 

[teapot]

Hi Aquaclear-NZ,
doesn't sound like algae, sounds like white mould (animal not vegetable) and it is quite resistant to chlorine, what type of filter do they have?

The mould can build up on biofilms inside the filter and pipework then begins to float free like tissue paper. You should be able to find evidence of it inside the filter or other places that are in darkness.

I would try to oxidise it out with your strong chlorine and monopersulfate and a biofilm remover.

EDIT: ppm 8-9 is not high enough with CYA at 50 you need to be 20-30 ppm to get a real shock

 

[JasonLion]

It is possible that there is algae and calcium flakes and the two independent effects have been mistakenly interpreted as single problem. Your description is an almost perfect description of calcium flakes coming out of either a SWG or heater. If the SWG has been removed as a possible cause, a heater is still a possibility (though that is a much less common cause of this effect).

Calcium flakes and white mould behave very differently when you touch them. It should be simple enough for the pool owner to tell you if the flakes are brittle or soft and slimy.

If this had been posted by a complete novice, I would also consider the possibility that the CYA level is very very low, despite the test result. That is another way to account for rapid FC loss, even though the CYA test result argues against it.

 

[chem geek]

If the white flakes are more like tissue paper and easily fall apart, then this is more likely to be white water mold; if the flakes are more solid, then more likely to be calcium carbonate. If the flakes can be collected, then if lowering the pH dissolves them, it's calcium carbonate.

The fact that they disappeared with higher chlorine levels does seem to indicate white water mold, though usually that doesn't grow in a chlorine pool unless the chlorine level got too low. Perhaps the chlorine got below 2.5 ppm FC with 50 ppm CYA for an extended period of time or there may be an area of the pool with poor circulation. As teapot noted, you would need to shock at a higher level of at least 20 ppm FC to kill off this mold.

As Jason wrote, there could be multiple things going on at the same time here.

 

[Aquaclear-NZ]

thanks guys - unsure of heater, and in fact it didnt cross my mind, however if there is one on site (i will confirm) it will be a titanium heat exchanger unit

Apparently the shop is sending me a sample by post, my fingers are crossed the envelope doesnt rip mid transit and cause panic in the post office

initially i looked at the chlorinator - as the description of the white flakes was what you would expect to see coming off a salt cell - large, brittle white flakes
however after a week of having no swg they are still appearing (thanks for the heater suggestion jason - there is a good chance it could be a scaled heat exchanger,). it is a fairly short return to the pool from the filter - somewhere in the 15' range

They have raised chlorine up to 10ppm for a couple of days, retested in the morning and found loss to be around 2.5ppm overnight

water has been cloudy since raising chlorine level - so will see what happens over the next day or so, also will see what arrives in the post