Second season with Algea - help

[UnderWaterVanya]

One thing I did not see suggested is to leave the cover off during the day some. The recommendation when shocking is to do this normally. Even if you only did it a few hours a day you might see some changes.

Also with the CYA test - are you measuring in full sun (back to the sun) from waist high?
CYA from dichlor and trichlor should show up really soon - it's odd that you have added enough for 40ppm but only test for 20ppm.

 

[SingingSailor]

Many thx for your replies!

I have at least a km to nearest industry or agricultural site. There´s nothing I know of that give large waste into air. Have no signs of downfall on the cover. I´m no expert, but have no ideas of what could possible be coming from the atmosphere. Ideas of what to be looking for?

The liner is standard vinyl I believe - it´s an Intex above ground pool. I have some plastic tubing in the system that´s not normal pool equipment, I have wondered if they could be causing the faint "plastic" smell. I have also a stainless steel heat exchanger that´s not normal pool equipment either. I´ve had some corrosion problems with it during winter, but not noticed anything in season. Finally I´ve used a home-made clear plastic cover now and then. Everything else is standard pool equipment .

At startup with new water, I get a brown cloud in the water when chlorinating, it forms a dust on the bottom. This I believe is Iron from the fresh water. It does though only form on the bottom.

Do you have any ideas of possible inorganic sources that can cause this? Especially depositing on walls, easily removed, and the different colors green / yellow / brown I see.
Chlorine does at least have a bleaching effect on this stuff - I put the cloth used for brushing in a bucket of more concentraded chlorine, and the brown residues after brushing is bleached over night.

Regarding the cover - I do keep it off now and then, don´t think it would matter.
CYA test: I´m certainly a beginner in testing. Last time it was not full sunshine, but possible misreading because of this would give me a false high CYA, not the opposite? I read also that beginners tend to interpret the CYA too high.
There has been quite a lot of rain this year, so there has been some dilution of the pool water, but I don´t think it could explain the whole difference between calculated added 40 CYA and the measured 20 CYA. But I tend to trust the measurement more.

 

[Bama Rambler]

1 km (.62miles) is pretty close depending on what they're putting in the air. You may not even be able to see it but it'll collect in the water.

 

[SingingSailor]

Opening this thread again, to give some feedback to the forum and maybe get some help.

I took a sample of the brownish slush to a lab last autumn, and had some pictures taken, see attachments.
They definitely identified it as green algea, but could not say exactly what species.

So, I´ve got algea that grows above shock level FC, and doesn´t consume much FC...

I´m now about to open the pool again for the season, draining all water and refilling with fresh.
I got an advice to spray the pool with 1:10 clorox solution. Don´t have clorox, but can mix a strong CalHypoclorit solution - what FC level would that be?
What would be the maximum FC level you would recommend to run through the pump system? I´ve got a stainless heat exchanger, I guess that it is the limiting component.

I think I´ll be trying with polyquat this season, haven´t used it much before. Will it impact the chlorine consumption?

 

[duraleigh]

So, I´ve got algea that grows above shock level FC, and doesn´t consume much FC

I haven't reviewed this thread but I am pretty confidant algae will not grow above shock level....regardless of type. Actually, it won't get started growing at normal maintenance levels but shock value, applied properly, kills it. You must have had a different experience.

Polyquat is a fairly good PREVENTER of algae but not a very good killer. I wouldn't waste my money.

 

[SingingSailor]

Yes, it seems I managed to stop it by shocking at high levels and brushing, but it kept coming back several times, and it seems to have a bit low sensitivity to chlorine.
- starts growing at FC 2ppm (CYA around 10)
- passed OCLT at FC 12 ppm several days (CYA 20-40), but still growing

I saw today that I have a lot of green algae under the liner: Liner has a pattern of blue squares with white bands in between, and I have the same pattern with light green growth under the white parts of the liner, especially in the sunniest corner.

I read somewhere that algae can pass through a vinyl liner.
Is that really true?
If so, it would clearly explain why the algae keeps coming back.

 

[chem geek]

Though the low FC/CYA ratio may have let this get started, it does sound like you may have a species of algae that is more chlorine resistant. Usually that's yellow/mustard algae while green algae is easier to kill, but yours is more like green algae in appearance. Very unusual.

As for whether Polyquat will help prevent this in the future, that's hard to say since this seems like a rather strange algae. You can certainly try using it during the latter part of next season and see what happens or you can just maintain a higher FC/CYA level. For now, you've got to kill all of this current outbreak by maintaining shock level and brushing. Part of the problem might be poor circulation since Intex pools are notorious for that.

 

[SingingSailor]

Thx, I'll try with poly also, and a lot of brushing might be more important if I have bad circulation.
No outbreak right now, I've emptied and cleaned for start of season. Will fill fresh water now.

How about algae under the liner, can it pass through?

 

[duraleigh]

How about algae under the liner, can it pass through?

No

 

[SingingSailor]

Reviving my own old thread with aftermath and some questions.

My algae problem continued through the seasons 2013 to 2016. I did several improvements during these years – changed to larger pump with sand filter, increased tubing size, added a very fine filter bag to the pool inlet when vacuuming (it effectively stopped algae from returning to pool). Algae kept coming back though, and I simply had to live with some algae and brushing and shocking several times per season when it grew too much.

A possible source of the algae I learned could be our public outdoor pool, which has a constant slow growth of algae at the pool bottom in spite of professional grade chlorine systems. As we frequently swim there we probably could bring algae with us in the swim wear.

In 2017 I got a tip from a friend and I changed from ordinary trichlor pucks to an “all-in-one” chlorine puck. After that I had no sign of the algae at all in the whole 2017 and 2018 seasons! I then closed the pool out of ageing and low usage in the end of 2018.
This puck consisted of Trichlor (in both quick dissolving and slowly dissolving form I think), aluminium sulphate, boric acid, citric acid (!?), copper sulphate and PBTCA. I think these are for sanitizing chock+longterm, flocculant, pH stabilizing, algae prevention, scale prevention.
My guess is that the copper sulphate is what helped stop the algae, maybe in combination with some of the other ingredients and the lower usage of the pool.

What are your thoughts about this?

Now we have just bought a hot tub, and I don’t want the history to repeat itself.
Algaecides, like polyquat, is often recommended also for hot tubs in Sweden. (I tried also polyquat in my pool, didn’t help at all).
If there’s the slightest chance though for this demon algae I had in the pool, it surely will come back… I hope good handling of chlorine should be enough, and I don’t want to add copper if I can avoid it.

Do you think I need to worry about the algae in my new spa?