Algae survival?

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goodnterribles

0
May 27, 2008
26
Cary, NC
so i am completely stumped at this point: i had algae at the beginning of the season because of a broken pump, got this fixed and followed the algae advice in pool school, and got rid of it (or so i thought). the last few days, i have seen what HAS to be algae growing on the walls, especially around the pool light and ladder. i can send a pic later if need be. anyway, here is why i am stumped: my numbers have been perfect the last month, i have only let my FC level drop below 4 one time, and i immediately bumped it up to 5. here are my #s tested last night and then this AM:
FC 5
CC 0
TC 5
TA 80
PH 7.5
CYA 50-60 i know i need to get this back up, we've had a ton of rain here

overnight, i had no FC loss. is this still algae that has hung around that i wasn't able to completely kill? is it even possible for algae to survive that long in water that has sufficient FC levels?

any explanation would be very helpful. thanks!

eric
 
Post a pic. Mustard algae can be resistent to normal FC levels. It requires high shock levels to attack and high normal levels to prevent from returning. It's possible you have FC "dead spots" where during the day, certain areas of the pool drop too low during the day, from uv loss and the algae possibly lurking. So if you can post a pic that would help us i.d., Usually FC holding overnight indicates it's not algae though.

How much run time do you give your pump, and does it run at all during the day?
 
that's what i thought about the FC holding overnight too, that's why i'm stumped. when i get home i'll take a pic and post it.

i run the pump anywhere from 10-12 hours a day (usually from 9 am-8 pm) with the SWG set on 20% (sometimes 40% if it's really sunny or a lot of people swimming) and it's kept my FC very steady.
 
ok, so i need to revisit my issue. i thought i got rid of whatever this was but it is back and "better" than ever. i ran the aquabot all weekend and also shocked to MA level. my current levels are:
FC 17
CC 0
TA 70
ph 7.5
CYA 50-60

i haven't had overnight FC loss although i didn't test last night, but will tonight/tomorrow AM. here are some pics of my pool, there is some dirt in there from some rain last night. please, if anyone has any answers, i am all ears! thanks!

eric

Pool2.jpg

Pool1.jpg
 
See this chart:
http://www.troublefreepool.com/chlorine-cya-chart-t2346.html

After you complete the shock process, keep your FC at the Mustard Algae minimum for a month or so. Make sure you treat all pool toys, ladders, etc. while at shock level, and check in any trouble spots that get poor circulation.

Not saying it's for sure Mustard, but might as well err on the side of caution.
 

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goodnterribles said:
how do you know if you've gotten rid of it?
Click to expand...

It doesn't come back. :mrgreen: :lol:

I guess you don't, until you see it come back.... Just shock for a couple of days, treating all areas where it can hide and pool toys carefully (wash suits and towels in hot soapy water), then maintain the higher FC level for a few weeks. It may take a routinely higher FC level in your pool. Every pool situation is different.
 
The Mustard Algae routine goes like this...shock to Normal shock level for a couple of days until no FC loss overnight. Raise up to MA level for 24 hours, making sure all pool toys, ladders, floats, ect have been exposed to the shock, brushing poor circ areas like behind ladders, light niches etc... Then maintain the higher "min" and "target" for a few weeks or so, ensuring it doesn't return. Running at the higher "min" and "target" doesn't hurt anything at all, just costs you more for bleach. The MA shock level is only for a short time and it won't hurt anything either.

Prolonged periods of MA shock level can fade a liner, but we don't recommend that.
 
X-PertPool said:
I don't like maintaining such a high FC reading in a pool for so long. I use Yellow Treat Plus for a quick solution IMO
Click to expand...
See this post. FC by itself means almost nothing without knowing the CYA number. FC is simply the chlorine capacity or reserve, but does not tell you the strength or activity of the chlorine. Even at the yellow/mustard algae shock level of an FC that is roughly 60% of the CYA level, this is technically equivalent in terms of chlorine strength (reaction rates) to an FC of only 1.4 ppm FC with no CYA.

Many indoor pools, most of which don't have any CYA in the water, have higher active chlorine levels. My wife experiences this every winter season when she has to use a community center pool that is indoors with 1-2 ppm FC and no CYA compared to our own outdoor pool in the summer with 2-5 ppm FC (normally 3-4) and 30 ppm CYA. Her swimsuits degrade (elasticity gets shot) after just one winter season while in our own pool in the summer they last for many seasons. Her skin is flakier and hair frizzier after using the pool with no CYA over the winter while in our own pool even in the sun these effects are minimal. The difference is that the active chlorine (hypochlorous acid) concentration in the indoor pool with no CYA is 10-20 times higher than in our outdoor pool with CYA. Having 30 ppm FC with 50 ppm CYA is not nearly as harsh as it sounds.

When you use Yellow Treat Plus (see here), you simply convert your pool to a bromine pool and bromine does not combine with CYA so you get "full-strength" of bromine. You simply work around the CYA, but in terms of harshness it is no different than simply raising the FC level with chlorine when there is CYA present. In fact, Yellow Treat is roughly the same as the mustard/yellow algae shock levels of chlorine. At one pound (of 88.8% sodium bromide) in 20,000 gallons, this raises the bromine level to 5.3 ppm bromine which is equivalent to 2.3 ppm chlorine with no CYA so is roughly similar to mustard/yellow algae shock level.

Richard
 
ok, well i got my FC up to 23.5 last night. this morning it dropped down to 17.5. it could be the algae but we also had a thunderstorm in the middle of the night and i found 2 dead mice in the skimmer :( i am gonna keep the MA shock level for a few days, and then let it gradually drift down to the high FC target.
 
You don't want to do the MUstard Algae shock level for more than 24 hours - it could fade your liner. If you maintain normal shock for a few days with NO overnight loss, then boost to MA level for 24 hours, then let it drop to MA-Min levels, that should do the trick.
 

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