Green Algae and High Phosphates
Free Chlorine 3.0
Alka Pool Store said OK, test kit said around 170
Acid - OK
Last Friday pool (25,000 gallong with sand filter) was clear, Sunday morning it looked like a green swamp. Pool store sold us Banish which we put in and added 1 gallon chlorine that evening. Next day no change. Shocked pool with 4 gallons liquid chlorine. Next day, no change.
Pool store said phosphates were high, so treated with Phosphate Remover (12 oz.) plus 4 oz. of clarifier. Still no change.
Have been backwashing throughout when pressure reaches 10 lbs. or more over normal. Vacuumed to waste on Wednesday and then shocked again with 4 gallons of liquid Wednesday evening. Thursday a.m. pool had changed to aqua color but water still very cloudy and some green areas on pool bottom...which we are starting to see again in shallow end.
Phosphates still 1000, so pool store said add 16 oz. more of phospate remover. Backwashed this a.m. and white stuff was in the water. Have also been adding a D.E. concentrate powder to the filter. Now are waiting another 24 hours to see what happens as Phospates are still at 1000.
Should we be doing anything differently?
Thanks for the question Julie
Your situation is the reason I put this site up in 2008. First, I'd like you to read this post which is very similar to your problem. It's long but worth the read.:
High Phosphates Over 1000 & Cloudy Water
Now for your issue. First thing is to stop using phosphate remover or clarifier. They're going to cloud up the pool, don't contribute to clearing it up, and don't tell you why the pool was cloudy or green in the first place.
According to Bioguard MSDS sheet, Banish is nothing more than a generic copper/metallic algaecide. It does nothing to remove/kill algae from the pool. If you're going to use an algaecide, it's best to use a PolyQuat 60. This contains no metal and is safe for vinyl liners. Keep this in mind because I'll return to it shortly.
First is to get the total alkalinity (TA) down to 80 - 100ppm, 120ppm being the top. It's 0.8 qrts. of acid per 10,000 gallons of water to reduce the TA 10ppm. You have a 25,000 gallon pool and the TA
is 170ppm. You need to reduce it at least 70ppm so you'll need 3.5 gallons of acid. Add 1.5 gallons of acid to a bucket filled with pool water and stir with a stick. With the pump OFF add to the deepest part of the pool and very gently sweep the bottom to break up any hot spots of acid. Allow to sit for 3 - 4 hours, then pump back ON to FILTER for 8 - 10 hours and retest. Make another adjustment if needed. Test the pH as well and make sure it doesn't go below 7.0.
The CYA is fine so don't touch that.
Now it's time to shock the pool. Shocking is a process, not an event. The trick is to get AND keep the chlorine above 10 - 12ppm for a period of time. You'll need to manually dose the pool with chlorine to keep it at 10 - 12ppm. Make the adjustment at night, then retest in the morning. Be sure to have the pump running 24/7 and backwash once per day. You can go up to 15ppm, but no higher. Anything after that and you're wasting money and chemicals.
You'll know this is working because the pool will go from green to a white/gray cloudy and the chlorine will begin to hold better. First you may lose most, then 2/3, then 1/2, and so on. Once you only lose 1 - 2ppm of chlorine 8 - 10 hours after the last application you know the algae is dead. Now it's just a matter of filtering and backwashing once per day.
Swimming Pool Chlorine
Back to the algaecide. You can use a PolyQuat 60 during the shocking process as insurance against another algae bloom. Remember, an algaecide isn't to kill already existing algae.
Here's a good post about putting DE in a sand filter:
Is Using DE In My Sand Filter Good?
To sum it up:
TA to 80 - 100ppm
pH to 7.2
CYA is fine
Shock the pool
FILTER and BACKWASH
If you would like personal assistance, I do phone consultations for a donation of your choice. It makes things go much faster. If you choose to not go that route, we can correspond by email.
Hope this helps and have a great Summer.