Yellow algae won't go away!

red-beard

Gold Supporter
May 27, 2019
552
Houston, TX
Chlorine is more effective at lower pH.

Seriously, I fought this stuff for YEARS. Only getting the CYA down, then SLAMing and maintaining the higher end levels of FC will kill this stuff. You also need to pull your lights and clean out the niche(s). Look everywhere. See my post about finding algae in the nuts of my Polaris 280.
 

mgtfp

Bronze Supporter
Mar 5, 2020
425
Melbourne, Australia
Not sure what's going on there. But you can't really keep staying at Mustard Slam level, that can't be good for your equipment or the vinyl liner.

One thing is to clarify that CYA level. I have no idea how trustworthy the Pentair kit is. I'd usually trust the Taylor test, but maybe you got a dodgy batch. I'd suggest to order fresh reagents from Tftestkits. Also get the 50ppm CYA standard sample. That allows you to verify your test procedure.

And just to confirm: You are not using the Pentair viewing tube with the Taylor reagent or vice versa? I am not sure if the reagents are compatible.

Then at least you'll know if you have to further reduce that CYA in your pool, and we're sure that your SLAM level is right. Until then, you should probably maintain SLAM FC according to the Taylor test. But that allows you to at least use your pool in the meantime. And keep thinking about other hiding spots where that algae could survive.
 

Macysumo

Silver Supporter
Jun 27, 2020
37
Pensacola Florida
I'm not cross mixing the Pentair or Taylor reagents. Just using them independently because I know it is a likely problem area. I like the idea of a standard sample...a calibration. Is that something I can buy locally or only the internet.

I'm still looking for places the mustard algae could hide. The LED light is out of the niche on the pool deck and there is no other source in the pool that I can imagine... maybe the skimmer (don't have a bottom drain). I've taken off the outlet eyes and cleaned them. I shut down and bypassed the filter for a day after deep cleaning and that didn't help. I have a pool heater that the water flows through when the pump's active but I have no clue how to service and clean the inside of that monster.

I'm not going to add chlorine tonight since FC was 28 ppm at 3PM today and heavy overcast. Can't keep this SLAM level . I may go back to Cal Hypo 73 as I have had better success with it previously (it came back but much later than daily).

Scratches head.
 

mgtfp

Bronze Supporter
Mar 5, 2020
425
Melbourne, Australia
I'm not cross mixing the Pentair or Taylor reagents. Just using them independently because I know it is a likely problem area. I like the idea of a standard sample...a calibration. Is that something I can buy locally or only the internet.
Cool, thought it's better checking that out, before we all go "duh" in the end. I don't think local shops will have calibration samples. I know that TFTestkits offers them, Taylor probably, too.


I may go back to Cal Hypo 73 as I have had better success with it previously (it came back but much later than daily).
I don't see how cal-hypo would be different there, chlorine should be chlorine. The only possible difference would be that undissolved cal-hypo might be lying directly on the algae for a while, creating locally much higher chlorine concentrations. But that's actually not a good thing to do with a vinyl liner, all chemicals should get pre-dissolved with a vinyl liner.

Cal-hypo will also increase your CH. Adding enough cal-hypo to raise FC by 10ppm, will also increase your CH by about 7ppm. You might run from an algae problem into a scaling problem. Have you tested your CH, can't see it in your PoolMath logs? And do you know the CH of your fill-water? If you have low CH, a bit of cal-hypo is fine (especially if you have to increase your CH from time to time anyway), but those with high CH in their fill-water try avoiding it.
 

Macysumo

Silver Supporter
Jun 27, 2020
37
Pensacola Florida
Have a new area to check today (yes, I’ll inspect the skimmer too) for algae source.

Did have a roof-mounted solar heater but recently put a metal roof on and unmounted the solar panels and distribution piping. The Pentair LX220 and the Compool CVA-24 valve actuator that controlled the solar water release into the pool is still mounted but in the closed position. The PVC that went to/from the roof is closed off and drained but the pool feed goes through that valve assembly. Might it be the/a source?

i could remove that whole section but there‘s a check valve in there too. Is that still needed or can I eliminate that when I replum?
pictures below...
 

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Macysumo

Silver Supporter
Jun 27, 2020
37
Pensacola Florida
Cal-hypo will also increase your CH. Adding enough cal-hypo to raise FC by 10ppm, will also increase your CH by about 7ppm. You might run from an algae problem into a scaling problem. Have you tested your CH, can't see it in your PoolMath logs? And do you know the CH of your fill-water? If you have low CH, a bit of cal-hypo is fine (especially if you have to increase your CH from time to time anyway), but those with high CH in their fill-water try avoiding it.
Calcium Hardness 125 ppm. Don‘t really don’t know what that should be in my vinyl pool (or if it matters) but it appears low according to Taylor’s quoting Industry Standards of 200-400 ppm... causes issues with concrete surfaces which I don’t have.
 

Macysumo

Silver Supporter
Jun 27, 2020
37
Pensacola Florida
Thx, Maddie... it says 200-400 ppm but claims to be titanium and "will be nearly impervious to water chemistry damage. However, other components of the heater, and the remainder of the pool/spa equipment in general, may be susceptible to damage from prolonged exposure to unbalanced water chemistry." Nice to know.
 

Macysumo

Silver Supporter
Jun 27, 2020
37
Pensacola Florida
Felipe (flying tivo) how did you get that weir door off the skimmer inlet? I seem to have same Hayward skimmer.
Must I take all the screws off and remove the panel? And then what? Pictures?
 

mgtfp

Bronze Supporter
Mar 5, 2020
425
Melbourne, Australia
Calcium Hardness 125 ppm. Don‘t really don’t know what that should be in my vinyl pool
With the vinyl liner you don't have to worry about low CH (apart from the heater). But you still don't want it too high, scaling can affect all pool types. If your CH is now 125ppm, then you probably don't have to worry about that.

But I still wouldn't use cal-hypo as your main source of chlorine. If you added about 4ppm worth of cal-hypo a day (120ppm per month), you'd increase your CH by about 85ppm per month. It can still add up over time, depending on how much water lost by backwashing and splashing you replace (evaporation doesn't count, calcium remains in the water). Just keep an eye on CH when using cal-hypo.

Regarding the solar return pipe: does that end in its own pool return, or does it meet another return line? Could you check with a bottle brush or something like that from the pool side if there is any gunk in there?

Is it possible to open the black valve (keeping the blue valves closed) in a way that allows flushing of the return line with slam water?

Otherwise, could you connect the "to solar" and "from solar" pipes so you could flush the whole circuit with slam water?
 

Macysumo

Silver Supporter
Jun 27, 2020
37
Pensacola Florida
The Solar return goes to the Aqua Pro1300 Pool heater (out of view on the side of the house), loops through there before hitting the chlorinator then out to the pool. It doesn't have it's own return.

I like the idea of connecting those Solar to/from pipes, opening that black valve and all the blue valves except the drains, looping through that link and flushing with SLAM water. Sure is a lot easier than dismounting it (at least for now). Should eliminate one more potential source. Those ball valves are pretty sturdy but could easily be tainted.
 

Macysumo

Silver Supporter
Jun 27, 2020
37
Pensacola Florida
Small amount of Yellow algae today...maybe a tablespoon size in total in the usual spots. FC now 16.5, CC 0. Other than pH changes I haven't added Chlorine for over 72 hours when I raised FC to 51 (Mustard SLAM with CYA 90). Still working to find the source...

Appreciate the support here. Now Silver Supporter of TFP.
 

Macysumo

Silver Supporter
Jun 27, 2020
37
Pensacola Florida
Mustard algae still pretty much gone today. Maybe a small amount in a slight depression in the bottom of pool. Still Haven’t added any Chlorine in four days. Hardly any change on FC from yesterday (-0.5 ppm, but high at 16) and today was bright sunlight all day. pH up to 7.8 and stable.

Found some bad stuff in the skimmer flap Styrofoam sure enough (pic of back side foam below). Scrubbing anywhere I can find...even minor deposits are getting the serious treatment.

So far, my best guess where the MA was concentrated is the volleyball net pole hole near the skimmer lid. Always standing water in there and when I went to clean it out the water ran straight to the skimmer lid and into the pool return. Could be why we first saw the Yellow algae after a rainstorm....it would splash in there. I poured chlorine in there and let it soak two days (and both sides of the net poles just in case). Right now I have a rag stuffed in there but plan to make a PVC cap to cover both Long term.
 

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Macysumo

Silver Supporter
Jun 27, 2020
37
Pensacola Florida
Not declaring the Mustard Algae over but with y'alls help I can say this skirmish has been won! Another night without MA appearance. FC dropped 0.5 (now 15.5) and zero CC. pH still drops (seems it likes low end of acceptable, 7.2-7.3) so I'm bringing that up to mid-range for now.

Even though raising the pH was not suggested when I was at SLAM level (and it could be totally unrelated) it was a point where the MA went from active to not.
 

Macysumo

Silver Supporter
Jun 27, 2020
37
Pensacola Florida
Made it through the weekend without a Mustard Algae breakout (except for some little depression that could be dirt but never showed before).
I've let Free Chlorine fall naturally and it's now at 7.5 ppm (losing 0.5/day) cc 0 and pH 7.5. We've had no violent storms for a week so I'm not calling this a win yet but hopeful I've licked it when the sun shines.

Still waiting on the CYA standard so I can calibrate my CYA testing and get more precise on what FC I need to keep the pool at going forward.
 

mgtfp

Bronze Supporter
Mar 5, 2020
425
Melbourne, Australia
Sounds like you are getting there!

Until you have certainty with your CYA, I'd assume it's 70, which means target FC is 8-10. After fighting Mustard algae for so long, I'd actually recommend to stay at the upper end of the target range for a while, rather a bit higher than lower. And try to not even come close to the min FC...