Ever Present Algae

[socal]

My Fiberglass pool always has a small amount of algae on the gasket area of the 2 inlets, vacuum port, 2 outlets, and skimmer.

Basically anywhere there is an entry/exit through the shell. It's always there, I brush it off and it grows back.

The pool water is ALWAYS year-round crystal clear, and the current numbers are:

FC = 4
CC = 0
PH = 7.4
CYA = ±45
TA = 60

Water Temp 73º

Two weeks ago I did the annual Super Chlorinate to FC 13, CC 0, at the start of the swim season

What is this algae an indicator of? How do I get rid of it?

10k Gal
SWG

 

[jblizzle]

There should not be any algae if you are maintaining adequate FC which is a function of your CYA: see the FC/CYA Chart

Those numbers put you right around the minimum your FC should ever be allowed. You should be raising your FC up to around 6-7ppm every day so it stays above 4ppm by the next day.

Your one time "super chlorination" is in no way what we teach. You need to follow the SLAM Process to ensure that you eliminate all the algae in the pool.

How are you chlorinating?

 

[pwrstrk]

If you have visible algae anywhere you need to follow the SLAM process.
Just what JB stated, you are at the bare min of your FC level for your CYA level. I wouldn't be surprised that it has slipped below your min on more than one occasion.
Slam the pool to rid it of algae and then maintain the proper FC levels at all times and you won't have any problems with algae. ?

 

[socal]

Thanks for the comments, but now I'm more confused.

I performed the OCLT tests:
7pm FC=5
7am FC=5

According to the OCLT page, "there isn't any living algae or other organic contamination in the pool", if FC remained the same.

Also, the CC=0 and the water is clear. Isn't that also an indicator that the water is healthy?

Not surprising the pool store says I have a phosphates problem @300, which is where the algae is coming from.

On a side note, what would the advantage be of raising my 45-50 CYA to the 60-80 range?
And what is the logic of targeting 60 vs 70 vs 80? Since I can add CYA to hit any of those targets, which one is 'optimal', 'best'.
Why would you want your SWG to produce 6 @80, when it could be producing 4 @60?

Thanks

10,000 gal
Fiberglass
SWG
Taylor K-2006
So Cal Desert Heat

 

[CumminUp07]

Did you have your SWG running during your OCLT?

 

[jblizzle]

Usually the OCLT test is done at higher SLAM levels of FC. But, you showed no loss, so that is good. When we say "water is clear" that also implies that you do not see ANY algae in the pool.

SWG add FC slowly. The higher the CYA, the more protected the FC is from the sun. At higher CYA levels, you will not lose as much FC and you may find you can turn down the SWG output, thus extending its life.

For example (made up numbers), with a CYA of 60ppm you may maintain 4ppm by adding 2.5ppm every day, but at a CYA of 80ppm you may maintain 6ppm by adding only 2ppm every day.

There is no "optimal" CYA level. The more sun you have, you may want the CYA higher. BUT, the downside is, if you need to SLAM, then the required FC levels get much higher as the CYA increases.

 

[socal]

Did you have your SWG running during your OCLT?

No, SWG was not running

 

[socal]

Usually the OCLT test is done at higher SLAM levels of FC. But, you showed no loss, so that is good. When we say "water is clear" that also implies that you do not see ANY algae in the pool.

SWG add FC slowly. The higher the CYA, the more protected the FC is from the sun. At higher CYA levels, you will not lose as much FC and you may find you can turn down the SWG output, thus extending its life.

For example (made up numbers), with a CYA of 60ppm you may maintain 4ppm by adding 2.5ppm every day, but at a CYA of 80ppm you may maintain 6ppm by adding only 2ppm every day.

There is no "optimal" CYA level. The more sun you have, you may want the CYA higher. BUT, the downside is, if you need to SLAM, then the required FC levels get much higher as the CYA increases.

So other than raising my CYA to 80ish, is my water safe? Do I need to take any action? The tests seem to contradict the fact that there is some algae. Keep in mind when I say algae I'm talking about a tiny amount just on the gaskets. This would be easier if the water was green and the walls/bottom had slim.

I would hate to run a SLAM just for the sake of doing it, but will if it is truly needed and the water is unsafe.

 

[ping]

How often do those areas get brushed? They might need to be brushed more often than what you doing, once a week should do it.

Your super chlorination level of 13 was not high enough to be considered at the recommended SLAM level for your CYA of 45. I suggest raising the FC to 18 and giving the entire pool a good brush down and run an OCLT that night.

 

[jblizzle]

I think what Ping is suggesting would be good. Not a full SLAM, but worth checking.

Even if the pool was covered in algae, as long as you had FC registering and could see the bottom of the pool it is SAFE. It is safe to swim even while you raise the FC level up to SLAM value.

 

[duraleigh]

I am going to suggest that those areas are indentations where the pool water (and FC) does not circulate sufficiently to keep out the algae......a very local low FC area.

You can clear them with a quick use of a deck brush every now and then or you could experiment by elevating your FC up to around 8 -10 ppm and see if it keeps them clear. That would certainly be more expensive but perhaps more convenient.

 

[socal]

I am going to suggest that those areas are indentations where the pool water (and FC) does not circulate sufficiently to keep out the algae......a very local low FC area.

You can clear them with a quick use of a deck brush every now and then or you could experiment by elevating your FC up to around 8 -10 ppm and see if it keeps them clear. That would certainly be more expensive but perhaps more convenient.

Do I need to hold the FC level at 10 for an amount of time, or just get it to 10 and let it drop naturally to 4-6?

 

[jblizzle]

I think Dave was suggesting that you would keep your FC at 8-10ppm indefinitely to see if that stopped the algae if you did not want to just brush every so often.