Yellow algae

poolcrazed

Member
Jul 23, 2020
22
Durhamville, NY
Hello, this is my very first post. I can't believe I haven't discovered you all before now. I am thanking you in advance.
My cool is very clear in the shallow end (3'), but very slightly not sparkly in the deep end (8'). A couple things going on: my Cyanuric acid level is now above 160, very small amount of what I think is yellow algae over the last few days. When I noticed it (very subtle) 4 days ago I brought down ph from 7.9 to 7.5 and alkalinity dropped from 110 to 103, raised chlorine to about 6ppm, added 19oz Bio Guard banish and have been vacuuming 1-2 times a day (even if no visible algae). I opted for conservative treatment bc it is very little visible algae, still appealing to swim, it's 95 degrees and our season is in total about 8 weeks! So did not want to super chlorinate it unless it really started to go badly. I know that is not the optimal strategy but I was trying to keep it so we could swim in this crazy hot weather. I did not realize until this week that CYA as high as it is is not good and likely contributed to the algae growth. I want to switch to liquid chlorine but not sure how to go about that (amounts?) and if I am seeing 4-5 very small spots of what I think is mustard algae but the pool water does not have a hint of discoloration, what should I do at this point and do you think it is unsafe for swimming? There was no visible algae all day after vacuuming yesterday morning and into the evening but saw a few spots this morning. This is the 12th year with this pool and last year in July was the first time I had any algae trouble (and I was not an algaecide user, just tried to keep things balanced and chlorine level ok- not crazy high but enough - or what I thought was enough). Thanks if you can help. Really wondering about the safety issue. Of course, if it looked horrible I would super chlorinate it - liquid chlorine was the only thing that worked last year - then it had that yellow tinge- not seeing that right now. Thanks.
 

Msch99

Gold Supporter
Bronze Supporter
Jun 11, 2018
908
Verona, MO
Welcome to TFP!😀
For starters you will need your own test kit. See test kits compared in my signature, but I suggest the TF100 with speed stir. The experts can then assist you once you post your own test results.

One of the TFP basics is the chlorine/CYA chart. (See link in signature). You will see that with a possible CYA of 160, your FC is way too low, allowing algae to take hold.
See also ABCs of pool water chemistry.
Good luck! 😀
 

poolcrazed

Member
Jul 23, 2020
22
Durhamville, NY
Welcome to TFP!😀
For starters you will need your own test kit. See test kits compared in my signature, but I suggest the TF100 with speed stir. The experts can then assist you once you post your own test results.

One of the TFP basics is the chlorine/CYA chart. (See link in signature). You will see that with a possible CYA of 160, your FC is way too low, allowing algae to take hold.
See also ABCs of pool water chemistry.
Good luck! 😀
Thank you but if I raise the FC to be coordinated with the CYA, can we still safely swim in it and do you know about the health affects with a trace amount of yellow algae but still mostly clear water? I will order a test kit now but worried about how to manage this in the meantime.
 

poolcrazed

Member
Jul 23, 2020
22
Durhamville, NY
FC at or below slam is safe to swim.
@mknauss about algae
thanks for your reply. This is a whole new concept of pool care for me! I will pull puck out and put in some liquid chlorine to try to get these bits of algae under control. I saw that along with mustard algae can come ecoli - no idea if this is true so that is why I have been worrying about swimming--if that's the case, then I will just blast it and have it off line even though it's crazy hot......
 

wireform

Silver Supporter
In The Industry
Aug 15, 2017
2,115
Spring Valley, NY
Poolcraze,
Get the test kit ordered real fast. It'll be you best friend till you get squared away. When you get the test kit run the full test and report back.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
37,186
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
I saw that along with mustard algae can come ecoli - no idea if this is true so that is why I have been worrying about swimming
To my knowledge normal pool algae is not harmful.
@YippeeSkippy -- any issues swimming in a pool with algae?
 

YippeeSkippy

Mod Squad
LifeTime Supporter
Jan 17, 2012
16,039
Evans, Georgia
From what I knoow algae is generally not a pathogen, perhaps ear external infections?

I can't imagine how E.coli could come into play??? Unless you had animal waste run off into a pool???

Maddie
 

poolcrazed

Member
Jul 23, 2020
22
Durhamville, NY
Too funny!!! It still look very inviting but Dang if I don't keep seeing very small patches of what I think is yellow algae. I am about to hit it with liquid chlorine. I have stopped using the pucks! I am reformed though I hate handling the liquid chlorine. Perhaps people have sorted out a trick to make this easier- a special pour top, for instance? CYA is 131 today. I will keep you posted. I'm sure I will need some hand holding. Who would have thought water could be so perplexing and complicated!
 

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poolcrazed

Member
Jul 23, 2020
22
Durhamville, NY
From what I knoow algae is generally not a pathogen, perhaps ear external infections?

I can't imagine how E.coli could come into play??? Unless you had animal waste run off into a pool???

Maddie
It was some random site that I read that. Maybe a pool company anxious to sell more algaecide..... the pools looks good. I can just see that overnight small patches of this are growing still.
 

poolcrazed

Member
Jul 23, 2020
22
Durhamville, NY
FC at or below slam is safe to swim.
@mknauss about algae
This concept just really blows me away. Why after all these years do I not know this stuff! this morning's agway test came in at CYA 131, ALK 108, PH 7.8. The combined chlorine went from 0 to 1.16 after adding a gallon of oldish liquid chlorine. I put in a bag of smart shock and am planning to put in 1-2 gallons of liquid chlorine to try to get rid of these small patches of yellow algae. Water still looks mostly inviting- slightly less sparkle in deep end than it should have but you wouldn't look at it and not want to swim in it. When this happened last year I brought the ppm up to 30 and then used chem out to bring it back down quickly so we could swim again. Do you have any guidance? Trying to make a quick save on this. I have just ordered my proper test kit. I feel so stupid for not knowing there was a solution to those horrible test strips. I am pretty obsessive about my numbers so should have been onto this years ago.
 

Msch99

Gold Supporter
Bronze Supporter
Jun 11, 2018
908
Verona, MO
No need for chem out, not even sure what it is. You can swim as long as your FC is at or below slam level. Which would be astronomically high with CYA >100!
The experts here will get you rolling to a crystal clear pool. Once things are balanced, not much maintenance, some chlorine and maybe acid to lower PH as it rises.
 

poolcrazed

Member
Jul 23, 2020
22
Durhamville, NY
No need for chem out, not even sure what it is. You can swim as long as your FC is at or below slam level. Which would be astronomically high with CYA >100!
The experts here will get you rolling to a crystal clear pool. Once things are balanced, not much maintenance, some chlorine and maybe acid to lower PH as it rises.
Thank you for your note. The pool is very clear. By tomorrow morning I may see a few small spots of the yellow algae but have raised the chlorine now to 11.65. CYA is 132 (according to Agway if it can be trusted) So when I look at the CYA chlorine relationship charts it looks like my suggested free chlorine level is 10-16 so I'm going in for a dip, even though before yesterday I would have thought this extremely dangerous to swim in.....Chem out somehow deletes chlorine, which in my old pool care days, I would have thought necessary--not knowing about the CYA/CHL relationship. Will keep you all posted. My kit is on the way. I may put in another 1/2 gal of chlorine tonight to see if the few spots that have been returning in the morning are gone. It was definitely right at the beginning of getting that yellow algae- there has just been a teeny bit and it hadn't affected the clarity much so it may have been a blessing. Otherwise I would have never known about this forum and this whole new concept to pool care!
 

poolcrazed

Member
Jul 23, 2020
22
Durhamville, NY
Hello again. The pool looks totally clear (so slightly off in deep end) but in the mornings I see small patches of what I think are yellow algae. They seem to come back to the same places but not always (ledge and side wall mostly). Here they are attached. I vacuum in the morning then it looks good all day until the next morning basically. After upping the chlorine level, I thought they may have changed color a bit- not so yellow-brown but rather darker in color. Overall the pool looks very inviting but I'm scared to spend much time in water with a ppm of 14-15 at this point. Looks like my range is 10-16 with a CYA at 132. But is that really safe? For so many years we have adhered to not going in if over 4 or 5 and I have kept it on the low end of normal, too. This is the 12th year I've cared for the pool and only last year and now this (again in July) did I have any algae trouble (or at least what I think is algae). Last year the pool did get that slight yellow cast to it--not this year. Perhaps if I didn't vacuum each day, it would turn into that. I am not sure. I tried to nip it in the bud since it looked the same to me as last year. Thanks for your thoughts and esp about the safety of water with that much chlorine in it. How could that be ok for lungs and skin?
 

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Katodude

Silver Supporter
Aug 22, 2017
1,288
West Palm Beach/Florida
Pool Size
15000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
My CYA is 60 and I am running my FC at about 15 now due to a black algae issue I had. We swim in the pool every day. No issues. If your CYA is really 130, and you wont know for sure until your test kit arrives you will be fine.
 

YippeeSkippy

Mod Squad
LifeTime Supporter
Jan 17, 2012
16,039
Evans, Georgia
I'm not positive that's yellow algae, to be honest? Can you get in and try to scrape some up and then spread it on a white card? Does it smear?

What happens if you scrub it? Any chance this is leaf debris which can also stain at times with tannin but that's often brownish.

Maddie :flower:
 

poolcrazed

Member
Jul 23, 2020
22
Durhamville, NY
I'm not positive that's yellow algae, to be honest? Can you get in and try to scrape some up and then spread it on a white card? Does it smear?

What happens if you scrub it? Any chance this is leaf debris which can also stain at times with tannin but that's often brownish.

Maddie :flower:
It vacuums up. There was none yesterday since I raised the chlorine to probably about 14 or 15 for my 132 CYA. And the water is sparkling clear. I did see about a 3" piece in one spot this morning. This is what it looked like last year and then the water did get that yellow algae cast-- no yellow cast this year. It was coming back in the same areas when it was happening. I don't think it's dirt.
I just need to get comfortable swimming in water with such a high FC level. Goes against all these years of pool care believing it is safe. My plan is to slowly replace a significant part of the water but it's 24000 gal so not super easy.
 

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