Algae or Pollen?

[Stuamurr]

Ive had a re-curring what I thought was Algae problem in an indoor hopper design pool, with what looks like algae sitting on the joins, corners and slope edges of the pool floor. I have superchlorinated upto 15ppm, brushed and hoovered, then extended backwashed and flocculate with goldifloc after every backwash

NOP Test Results:
FC 3.0
TC 3.5
pH 7.4
TA 100
CH 200
Temp 27
CYA 30
Langelier 0.1

Scotland, soft water calcium hypochlorite for all disinfection, the more I read on line the more it sounds like I have a pollen problem, Once I have cleaned, superchlorinated, hoovered and backwashed the lying debris returns within a few days. The pool holds 180,000L / 25,000 gallons and is filtered for 4 hours per day, I know this aint much but thats me got the owner up from 1 hour a day!

It is possible that pollen is entering via the seperate air conditioning units but I am really unsure as I have never experienced this before nor worked with a pool that doesnt have a plant room running 24/7

 

[PoolGuyNJ]

Pollen? This time of year? Indoors? I don't know about that one.

Scott

 

[Bama Rambler]

I'm not sure about pollen in Scotland this time of year, but I'd say the possibility of it being pollen is low.

Do the air handlers have filters on the intake side? Also, is it a forced suction or exhaust system?

What test method do you have?

Can you run an OCLT?

 

[Stuamurr]

I'm pretty sure the air-con units have filters, i'm really not sure but think they are exhaust.

Test using Lovibond Comparator and DPD re-agents.

I will be running an OCLT over the next few days likely starting tuesday following poolguynj's advice, but I don't have above 5ppm test available so it will have to be dilution test, which is what I usually do when superchlorinating.

I've been reading like mad all day today (teatime now here) and I do believe it to be mustard algae hiding somewhere, and it is being killed once it comes into contact with the main pool water body, leaving the spore to re-produce in an discrete location, I'll be pulling the ladders, lights and inside the auto-leveler etc on tuesday.

Stu

 

[Bama Rambler]

If the intakes are filtered it's not likely pollen. I don't think it's mustard algae either. I think it's just green algae.

 

[Richard320]

I've been reading like mad all day today (teatime now here) and I do believe it to be mustard algae hiding somewhere, and it is being killed once it comes into contact with the main pool water body, leaving the spore to re-produce in an discrete location, I'll be pulling the ladders, lights and inside the auto-leveler etc on tuesday.

Stu

Is there anything else that goes in and out of the pool regularly? If it's a therapy pool, a wheelchair, maybe? Or lane marker floats strung along a rope?

Could swimmers be tracking spores in from somewhere else, like the shower?

Just some things to think about.

 

[Stuamurr]

Just green algae hiding in a discrete location then? I will keep you updated once I start the deep clean this week

Good food for thought Richard, I am also going to take over the cleaning of the deck surround as I believe the cleaning regime around the deck to be inacurate, but that is more dirt than anything else.

Cheers!

 

[loop_pea]

Hello from the other end of the UK.

I normally test with a photometer which uses the same reagent tablets as a comparator I believe. I find that dilution works okay at 1:1 concentrations or even 1:2 but above that it all starts to get wildly out. Factor in the inaccuracy of the test, which is something like +-0.4ppm at 4.0ppm FC and you really don't have a clue where you are when superchlorinating the pool (that's the accuracy for photometers, but I don't think comparators are going to be better in that range - it all looks pink to me).

Anyway, the point is that if you're trying to kill algae then you'll want to know that you reached a high enough FC level for long enough to do the job. I worked with dilutions for a while when shocking the pool, but eventually this year I gave in and bought a FAS-DPD kit from Palintest. You can get them in the UK if you know what to ask for. It does make life easier. For everyday testing I still use the photometer.

I had a similar sounding problem to you, and it turned out not to be algae at all - it was rust particles from the handrail brackets collecting in the divots and edges of the pool. I'm not saying this is your problem, just that sometimes you have to think creatively!

 

[Stuamurr]

Hi Loop-Pea, good to hear from another Brit!

Yeh you are correct Tablet re-agents are more or less the same Lovibond and Palintest tablets are unofficially swappable in comparators and photometers from both companies, I do naturally realise that a dillution will give incorrect readings, even being super accurate with your measurments, which I am, using a syringe for 10ml of pool and 90ml of still water, containing no chlorine trace. I will though look for a drop test for chorline in order to achieve better readings when superchlorinating. If I need superchlorination to be 10ppm however ill usually go to a higher level than that anyway, eg 12ppm to ensure adequate level, given the constraints of reading chlorine at higher levels using DPD tablets.

Regards
Stuart

 

[Richard320]

If you two have found a source for decent test kits, post some details! We get a lot of Europeans and have no way to help them because they can't find decent test kits.

 

[Stuamurr]

I know of a supplier that has a good cost lovibond comparator but its only tablet testing to 4ppm chlorine and I have also e-mailed Palintest here in the UK, once I have heard back from Palintest I can certainly update.

Stuart

 

[loop_pea]

I spoke to Palintest last year and they sell the FAS-DPD kit, but there is a minimum order value and you would have to order two kits to get your money's worth. (I have the part number written down somewhere and it's on the kit as well but that's up at the pool not with me right now). I actually bought my kit from teapot, who used to post on this forum, and I assume he gets them directly from Palintest as he's in the trade. So I imagine that any pool store with a Palintest trade account could get these in stock if they wanted to - they've just never been asked!

 

[Stuamurr]

Deep clean carried out today, green algae in light coves, in the auto-leveller, a small trace around the top walk in step and also some lying venomously around the shower floor, scrubed the whole place with 12 litres of bleach, deck, walls, fixtures, fittings, toys etc and superchlorinated to over 20ppm with some of the bleach and calcium hypo, everything now lying in the pool overnight (cover too) for the hoovering and backwashing tomorrow, lights floating nicely under the cover so the chlorine can get inside them - I was amazed at the amount of nasties that was lurking inside them and the auto-leveller. Dropped 2l of bleach in through the leveller reservoir then pushed through with pumped pool water and then finished off by sprinkling cal hypo inside it to dissolve gradully, to absolutely aniolate anything lurking in the reservoir to pool piping ill also add some slow dissolving spa tabs to it tomorrow to give it a further shock.

My guess is that several small algae blooms have been constantly growing in these areas causing the algae that materialises to be killed by the normal residual and falling to the bottom of the pool, it is also possible the algae bloom in the shower area has been tracked into the pool on bathers feet.

Will see what tomorrow brings!