Can't get rid of the Green

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C

ccclark1

0
Jul 19, 2009
4
Pittsburgh, PA
Trying to clear a neglected pool. My friend (he grew up swimming in ponds, she did not) left on vacation and asked if I would try to clean up her green pool. It went from black in May when it opened to green now. I started Saturday with lots of 12.5% liquid shock (12 gals over a day and a half) finally the FC appeared to be holding at 10ppm according to their Aquachek test strips. after no noticeable difference in the green color, I took a sample to the pool store for a PINPOINT analysis.

FC - 3.5
CC - 0.2
pH - 7.5
TA - 173
CH - 140
CYA-9

So I can see that while I thought my FC was at shock level, it was not. The CYA is low but the weather has been cooperating no sun just rain and temps in the 70's. Tonight I put the last 2 Lbs of CYA in a sock (the other 2 Lbs I put in the skimmer before I read it can take a week to disperse and I had backwash). Tonight I put in the last GAL of 12.5% Shock, and I put in 72 Oz. of CAL-HYPO 48% because it was there. The Walmart test kit (not recommended) diluted with 1/2 distilled water showed 5-10 ppm TC. I know I need to be patient but I really want to see something other than green. My big Question is when the FC is maintained at shock level how long should it take to change from green to gray or milky. The pool guy said put in 6 bags of shock, and the sand filter was a problem I know it does not filter as well as DE, but does it have anything to do with the green color? Your help will be greatly appreciated.

Thanks
Curt
 
Unless you keep the FC level at or above shock level constantly you are defeating your efforts. Algae grows very quickly and will consume your chlorine as fast as you put it in. So get more 12% or you can use 6% (chlorox), whatever works out cheaper in your area. Of course you need to use twice as much 6%. You need to bring it above shock level and keep it there, so test very frequently, especially for the first 24 hours, hourly is ideal and add more chlorine as needed. At a minimum you need to test it thereafter 2 or 3 times per day and keep it at shock level until it holds overnight or loses less than 1 ppm overnight. Make sure you are brushing, vacuuming daily and backwashing (when your pressure gets too high).

Actually, IMO, the triton II sand filter is a really nice one and filters wonderfully. I wish I had one.

Do the best you can with the Walmart 6-way testkit (hope it is a fresh one). It would be better if you had time to get a proper test kit that we recommend but since it is not your pool and you are simply helping out a friend ... you will have to do the best you can with the 6-way and distilled water dilution. If you also have a pool of your own, then I highly recommend ordering a proper test kit for yourself.

Read the Pool School info and get acquainted with the Pool Calculator and you will know exactly how to dose the pool.
 
Did you test CYA with the Wal-mart 6 way and get any results?

IF the CYA really was 9, 2 lbs would only raise the CYA by 10 ppm in a 25,000 gallon pool (I assume the sig specs are the subject pool?). You need at least another 2 lbs.

The Sand vs. DE has nothing to do with the color. You have to kill the algae before the filter can get rid of the dead stuff.

You are running the filter 24/7?
 
Hi All,

Still green but but lighter. I,ve been filtering 24/7 since Saturday and brushing twice a day. I think most of the debris is off the bottom but visability is still just 1 foot. added more 12.5% liquid went to a different pool store(same chain different method of analysis, I have my doubts)

FC - 10 limit of their equipment
TC - 10 limit of their equipment
pH - 7.0
TA - 140
CH - 275
CYA-0
my test also shows FC greater than 10ppm.

My question still is at this level how long should it take for the algae to die?
also does FC at higher concentrations kill faster?(10ppm or 15ppm-is more better)
the pool in my sig specs is the pool I am working 18x36 3-9ft w/floor drain
I read that is better not to backwash frequently. starts at 16psi after backwash(I think it was 10-12psi at sand change)and climbs to mid 20,s after 10-15 minutes, how high should I let it go?
what about chemically cleaning sand? I saw another post that mentioned Waterbear's method but no link.

thanks for your help
Curt
 
I didn't bother with the CYA test, I am sure it is low. am I wrong in thinking since there has been no sun, and I've been backwashing and refilling, at this point it's not that big an issue. also was told cloudy water can give inaccurate readings. once pool is clear I will address the CYA issue.

I know that 8-10 psi is recommended, but the manual sez after a backwash if the pressure starts 4-6psi higher than inital start-up the filter needs to be chemically cleaned. I'm used to DE filters, just learning about sand.
 
Follow the manual then, I wasn't aware you had it handy.

No, cloudy water won't affect the CYA test, especially swampy/murky black/green water MIGHT, but not cloudy water. We had a pretty thorough discussion of that issue last year on the forum, and informal tests were done and it even pond water didn't alter the results any...and if anything it would read high. There is no way your CYA level is 0, even with backwashing, your level was near 20 before. It's too low to register on tests but it's not zero.

You must have 30-50 ppm CYA in your pool to maintain adequate FC levels. If you don't, you lose the FC to sunlight, even on a cloudy day, and you lose ground in clearing the water during the day. Do not wait to address this issue.

On Tuesday, your CYA tested at 9, and you added enough CYA to raise your level another 10. You should go ahead and add another 2 lbs today. There is no reason to wait, you need the CYA in the pool.
 
I put 3lbs CYA in the skimmer on saturday, and 2lbs in the skimmer on Sunday, before I read here (ABCs of Pool Water Chemistry) "you should avoid backwashing/cleaning the filter for a week."

I put another 2lbs in socks in the stream of the outlet monday. also read here(CYA definition on THE POOL CACULATOR) "Solid stabilizer can take up to a week to dissolve, so don't retest your CYA level for a week after adding some."

I don't believe the pool store test results

MY QUESTION IS AT FC 10PPM+ HOW LONG WILL IT TAKE TO KILL ALGAE? I've been above 10ppm for 48hrs and there is still green.
can it be dead and still green. I got large clear container and filled it with shocked pool water. and left it sit over night there was a small amount of concentrated green sediment on the bottom. could this still be alive?

thanks
Curt
 
it takes as long as it takes. there is no black and white answer. make sure you're running the pump 24/7 and brushing at least daily. the best way to speed it up is to test and add bleach to get to shock level hourly. without one of the recommended test kits (specifally the fas-dpd chlorine test), you have to keep shocking until the pool is clear and cc's are less than .5.
 
In theory, based on what you added, despite backwashing, your CYA could be in fact, HIGHER than 20, which means you aren't shocking high enough even at 10, which could possibly explain why it's still green.

It's so important to have accurate CYA tests, why we don't like strips OR pool store testing, because they are almost always off.

Try increasing the shock level to 12/13 see if that makes a difference.

POP- have some POP. :wink:
 

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