How Do I Clear Up A Green Pool

by Kristin
(New Hampshire)

Very informative site! I have bookmarked it for future use. :)

My husband and I put up an above ground Intex Ultra Frame 22 ft, round, 52 in. deep pool a couple of weeks ago. We slowwwwwly filled the pool (My husband was afraid of burning up the well pump) which I believe may be the cause for some of our problems. It took about a week and a half to fill. Based on other posts, I believe we must have about 10,500 gallons of water in the pool.

We also hooked up a saltwater system and after running the sand filter for a few days, I added only 1-40lb. bag of salt. I had mis-calculated and didn't realize it until 24 hours later. So I then added 6 bags for a total of 280 lbs. of pool salt.

After the salt dissolved, I hit the boost button and that ran for a total of 8 hours. (The pump has stayed on almost non-stop since initial start-up a week or so ago). As of this morning, the pool is still completely green so I've been doing some research today and decided to add some chemicals. So I have added 1 bag of Shock, which is supposed to be good for 10,000 gallons of water and I also added about 8 oz. of algaecide. I should also mention, I did the test strips that came with the pool and got the following results:

Copper 0
Free Chlorine 0.2
pH was above 8.5
Total Alkalinity was about 240+

The strips are very basic so I did buy a $22 kit from Walmart but will have to wait until the recent chemicals work their magic. Based on my situation and what I've recently done, do you think I am on the right track to clearing this thing up or am I in for a very frustrating pool-less summer?

Thanks for the question Kristin

I'd like to have the rest of your readings, namely the stabilizer (CYA) and hardness. I will assume because you have a new fill, you probably don't have any stabilizer in the pool. This is important to get because it will help decrease chlorine consumption and decrease the chlorine burn-off be as much as 50%.

The first thing you need to do is get the pH and total alkalinity (TA) down. The pH needs to be around 7.2 and the TA between 80 - 100ppm, 120ppm being the top. You have a pretty large jump with the TA. It needs to come down 140ppm so you better get some acid. It's 0.8 qrts. of acid per 10,000 gallons to reduce the TA 10ppm. You're going to need about 2.5 gallons. Do this in stages, not all at once. 3 - 4 applications should do it.

Get a large bucket and fill it 1/2 with pool water. Add 1/2 gallon of acid to the bucket, stir with a stick or PVC pipe and add it to the pool in one spot with the pump OFF. Sweep very gently to break up any hot spots of acid. Allow this to sit for 3 - 4 hours, pump back ON and FILTER for 8 - 10 hours, then retest and make another adjustment. It's best to do this in the evening, then retest in the morning. Test the pH as well because you might be hitting that
with the acid.

Pool Alkalinity

Total Alkalinity

Next is the pH. It's 12 oz. of acid per 10,000 gallons to reduce 0.2. Broadcast this around the perimeter of the pool with the pump ON and FILTER. Sweep very well and retest after 8 - 10 hours.

Swimming Pool pH Levels

Pool pH

Now comes time to shock the pool with Dichlor chlorine. This is a stabilized form of chlorine. Once you reach the 30 - 35ppm CYA mark, stop with Dichlor and go back to regular liquid chlorine. Be careful when using Dichlor as it can get out of hand quickly. For every 10ppm of chlorine added with Dichlor, you'll raise the CYA by 9ppm. For every 10ppm of chlorine added with Trichlor tabs you'll raise the CYA by 6ppm.

It's 1 1/3lbs. of Dichlor per 10,000 gallons of water to reach the 10ppm mark of chlorine. You're right with the pool being 10,500 gallons. You may want to go up to 1.5lbs. It's better to go a little over than under when you shock. 11 - 12ppm is fine. Normal range for the CYA is 30 - 50ppm.

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. Be sure the salt cell is OFF during this process.

If you're going to use an algaecide, I'd recommend a PolyQuat 60. The cheaper ones have metal fillers in them. Also be sure to test the water for iron. Well water normally has high metals and iron is the most common.

If the tests come back with high iron, you'll need to use a good metal sequestrant. Metal sequestrants that are based on HEDP, phosphonic acid and/or its derivatives are the most effective. Some popular brands are Jack's Magic Blue, Purple, and Pink Pink Stuff. This is normally not a one shot deal. A metal sequestrant does not remove metal from pool water. It holds it in solution until it can get filtered. Then you backwash the metal out.

Because metal sequestrants break down over time and get filtered and backwashed out, you will need to add a bottle once per week. Don't go for any of the Burnout Shock or Super-Duper Mega stuff. It's all chlorine, just in a fancy package that's marked up 400%.

For an average 20,000 gallon pool you will need 7-10 50lb. bags to bring your saline level to the correct reading of 3000-4000.

Salt Water Swimming Pools

Chlorine Generator

Be sure you know the range for your salt cell. Keep the salt too low and it won't produce chlorine. Too high salt and the cell might burn up. Once you get the algae under control you can go back to the salt cell. I'd encourage you to get a Taylor FAS-DPD K-2006 pool test kit. It's the best on the market. Strips are convenient but are not as accurate as the K-2006 kit.

Pool Water Testing

Water Testing Kit

Hope this helps and have a great Summer.


Click here to post comments

Return to Swimming Pool Algae.

Bluish Green Cast on Some Plumbing Fittings and Polaris Pressure Line/Hose

by Dennis

I just closed my pool for the year but noticed some issues that have me concerned. The Polaris pool cleaner feeder hose and scrub tail hose have a very noticeable blue green cast to them (the hose is normally white). The white rubber tires on the wheels appear to be somewhat gummy with blueish deposits on the hard plastic wheel rims. Also the large white plastic disk that frames the pool light also has some bluish deposits on it as well. This has never occurred previously.

Some Facts: Inground pool, 11 swimming seasons old, vinyl liner, vermiculite bottom, approx. 26K gallons, salt pool that uses Hayward Aqua Rite clorinator, Hayward sand filter, Hayward super pump, Polaris booster pump, 2 skimmers, 1 drain, 1 pool light. The pool water was crystal clear all summer, salt 3000 PPM, occasionally added calcium, cyanuric acid, salt. I did add some algaecide in May to clear a small algae stain in the pool bottom, which resolved.

Click here to post comments

Return to Swimming Pool Algae.