Green pool.....nothing is working!

BPool5

Member
May 29, 2020
19
Illinois
My pool has been unusable for a month. It's Intex 5,000 gallon, Krystal Clear pump. A month ago I noticed mustard algae and the pool got really cloudy. Went to pool store and bought yellow out and I believe that got rid of algae. Pool still super cloudy. Brought water sample in and CYA was 178. They advised I drain pool 1/2 way and refill which I did. Brought another sample and CYA was 130. Drained 1/2 way and refilled and next sample was 82. I'm on well water and every time I fill my pool it's green water. Went through this at the beginning of the summer also. Pool store told me to use muratic acid which I did but pool has gotten even darker green. Went from neon green to forest green. Brought another water sample yesterday and results are:
Free Chlorine .22
Total Chlorine .39
PH 7.4
TA 86
CYA 95
Iron .1
Copper 0
Phosphates 6
TDS 800

He told me to get algaecide and then shock and I'll have clear water. I bought a gallon of aglaecide at Home Depot and used 1/2 the gallon (according to instructions on bottle) and then about 3/4 lb of shock. Hours later still swampy green. Added the rest of the algaecide and another 3/4 lb shock and let pump run 8 hours and this morning still green. I ordered HTH super green to blue shock and HTH Super algae guard which both have great reviews and people showing their before and after pictures but everything I've done so far shows the same kind of results. Shock and by next morning pool will be clear. Nothing is working. My kids have missed out a whole month of swimming.

Please help!
 

CrystalRiver

Well-known member
Jun 19, 2020
334
Massachusetts
Stop with the pool store products. Algaecide prevents algae but does not clear it. Green to blue adds copper to your water, which you do not want. Your CYA is high, too high. You need to drain about 75% in order to get it down to about 30. Much higher and it's very difficult to SLAM. If you drain too much, it's easy to add a little CYA to bring it back up. If you drain too little, you're stuck with what you got, or else you have to drain again.

In short, your pool is green because you have no chlorine. What are you using to chlorinate your pool? Many solid forms (and some liquids) contain things you do not want. Very commonly it's CYA.

You need to decide if you want to follow TFPC or pool store advice. If you go TFP, you'll need to buy liquid chlorine and a good test kit. If you continue with the pool store, we can't help you with that. Let us know what you decide.
 

thetekgeek

Bronze Supporter
Jun 8, 2018
257
Nebraska
Do you have any way of testing your water yourself? Pool Store testing is notoriously bad and we do not trust it here. IF they are correct on your CYA test (hint: they probably aren't), you'd still need to exchange 1/2 of your water to get to a manageable level. CYA levels as high as yours are teetering on the end of unmanageable and attempting to clear algae from the pool will be almost impossible.

Please see this link - Chlorine / CYA Chart - Trouble Free Pool to better understand the relationship between CYA and Free Chlorine. How have you been chlorinating? If you've been using tablets, that will explain the high CYA.

You have a couple of choices ahead of you. 5,000 gallons is small enough to be managed as a seasonal pool, but also big enough that it is a pain to do a full drain and refill each time things go bad. If you decide to manage as a seasonal pool, follow this article: Guide for Seasonal/Temporary Pools - Trouble Free Pool

I started with a pool exactly the same size as yours. I had no idea what I was doing and found myself standing almost exactly where you find yourself today. I'd suggest you get a good test kit, there are two acceptable kits on the market today that the folks on this site trust. See this article: Test Kits Compared - Trouble Free Pool

In the interest of the limited time you have left in the swim season, I would suggest you completely drain the pool and give it a deep cleaning then refill it. While it is draining/refilling, order one of the recommended kits and read through Pool School. Table of Contents - Trouble Free Pool From there, you'll be armed with the tools and knowledge to never have to be in this situation again and you'll never have to sink your money into the endless pit of pool store advise again.
 
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batesjer

Gold Supporter
Silver Supporter
Jun 26, 2019
79
East Lansing michigan
Can you take a picture of your water? The green color could be algae but it sounds more like iron in the water coming from your well. Check out the seasonal pool link listed above. If you treat your pool as a permanent pool you will want one of the better test kits, if you choose to treat it as a seasonal pool a basic 5 way kit will work. Addressing the algae issue will require either a SLAM or a drain, clean, and refill depending on how you prefer to manage the pool. One of the experts on here will be able to guide you on iron removal if that is what is going on, but pictures will help a ton to nail it down.
 

poolnoobgrandma

Gold Supporter
Sep 15, 2018
504
Seminole, FL
The experts are going to weigh in, but pretty sure the advice will be: 1)buy some liquid chlorine (Home Depot HDX is fine); 2)Buy a good test kit (TFT-100 or Taylor 2006-C); 3) Get a good idea of your CYA, if it's over 100, drain and replace water (amount tbd) 4) SLAM (SLAM - Shock Level and Maintain - Trouble Free Pool)
You can do 1 and 2 immediately. You could add chlorine, but if you are going to have to do a big drain, it may be better to do that first, then SLAM.
I've been following TFP methods since our pool was built, and have never been to a pool store. Our water is crystal clear and sparkling.
 

thetekgeek

Bronze Supporter
Jun 8, 2018
257
Nebraska
That test kit should be ok IF you are going to manage as a seasonal pool. At the very least, it could help you get through the rest of this season. It cannot test for CYA, which is very important because each tablet you use adds CYA to the water. CYA acts as sunscreen for your chlorine. However too much of it in the water binds the chlorine up so that it cannot sanitize. That is why we follow the CYA/Chlorine chart I linked to in my earlier response.

Did your pool store guy suggest anything to use in place of the tablets? Hopefully, Liquid Chlorine/Bleach? That water NEEDS chlorine.

I'd proceed with a full drain. Then scrub the walls, floor and ladder with a mixture of bleach and water. Get all that green out of the pool. Refill. Put 20 ounces of dry stabilizer into an old tube sock and hang it in the pool in front of the return. Squeeze the sock every 15 minutes or so to help it dissolve. This is 30 PPM of CYA in 5000 gallons. From there, the only chemicals you'll need are bleach/liquid chlorine and muriatic acid. Depending on the concentration of bleach you can find, you'll want to add enough to get to 6 ppm FC. You'll use your drop test EVERY DAY to test the chlorine level and add enough bleach EVERY DAY to get from the amount you determine on your test back to 6 ppm, never allowing FC drop below 2 ppm. Every few days, you'll want to use the PH side of your test kit to test and adjust PH, PH adjustments are done with muriatic acid, but NEVER at the same time you add bleach, always allow 15-30 minutes with the pump running between additions of either chemical.

Download the PoolMath app. It will help you with all the calculations to determine how much of each chemical to add each time you test. Or, you can use the old pool math webpage - PoolMath

Post back with any questions, the experts here are always eager to help. This site has taken me from where you are today (5000 gallon round ABG pool with algae outbreak) to a 17000 gallon inground pool that you almost are afraid to jump into because the water is so clear you're not actually sure there's even water in the pool!
 
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Dtkokay

Well-known member
Dec 31, 2019
317
Houston, Texas
Honestly, with only a 5K gallon pool, it seems like you should drain the entire thing and start over unless water is incredibly expensive in your area.

To summarize the advice above, you need to maintain a proper level of FC (free chlorine), and too much is way better than too little. The minimum amount of FC you need to maintain is based on your CYA level.
 

BPool5

Member
May 29, 2020
19
Illinois
What I'm unclear on is how will I not wind up with the same green water if I drain & refill? I just drained 1/2 way and refilled and then drained 1/2 way and refilled last week. Then went through the whole muratic acid treatment. Why will draining and refilling again yield different results? Seems I'll go through another week of all this effort to be sitting here next week saying my pool is green again.
 

DAB942

Gold Supporter
Nov 13, 2017
511
Space Coast, FL
CYA (stabilizer) is very high, which will limit the effectiveness of chlorine in the pool. In my sig, you'll see FC(free chlorine)/CYA chart. This will tell you how much Chlorine you will need to have vs the amount of stabilizer in your water. The acid is for your PH, which is separate from your chlorine levels. The FC/CYA chart will show your ideal CYA and corresponding chlorine level for your pool. What you need is more effective chlorine in the pool.
 

bonsey

Well-known member
Oct 7, 2018
82
PA
As mentioned, I would first recommend a better test kit. Either TF-100 at tftestkits.net or Taylor K-2006C. This will allow you to properly test during a SLAM everyone here mentions.

The pool is green because of the algae. It has algae because the FCL was/is too low for such a high level of CYA. Since you have a smaller pool, it would probably be easier to drain and refill then to try and start a SLAM at such high CYA. And by draining again, this will help lower your CYA to an acceptable level and not need so much liquid chlorine to SLAM and get the pool clear. If you only partially drain/refill and your CYA is lower, use the Chlorine/CYA chart to SLAM your pool with the proper amount of liquid chlorine and keep it at that level until all conditions are met and the pool is clear. Here is a link that explains the SLAM SLAM Info. If you completely drain and refill, you probably would not need to do a SLAM, but clean all the susceptible algae areas before refilling, then refill and test your CYA and get your FCL to the at least the target range listed on the Chlorine/CYA.
 
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Poolidiot

LifeTime Supporter
Mar 31, 2007
479
Texas
What I'm unclear on is how will I not wind up with the same green water if I drain & refill? I just drained 1/2 way and refilled and then drained 1/2 way and refilled last week. Then went through the whole muratic acid treatment. Why will draining and refilling again yield different results? Seems I'll go through another week of all this effort to be sitting here next week saying my pool is green again.
Here is what mine looked like last Friday and then what it looked like Sunday. All by using what this site says to do.
 

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thetekgeek

Bronze Supporter
Jun 8, 2018
257
Nebraska
@BPool5

I am recommending a full drain, clean and refill for two reasons.
1. You really don't know your true CYA level, and we don't trust the pool store test. Plus their advise got you here.
2. You have no way of testing CYA.

Once you drain and refill, we will know your CYA level, that is because there will be no CYA. In my post earlier I told you that after your refill, you should add 20 ounces of dry stabilizer to the water. At that point, we know your CYA level (30) so we can now guide you on the amount of chlorine your pool needs. That amount is 6ppm target and 2 ppm minimum. At that point, you can use the test kit you have (it tests up to 5 ppm) to add the proper amount of liquid chlorine/bleach to your pool EVERY DAY so that the pool never has less than 2 ppm. If you are able to do that, the algae will not come back.

The muriatic acid is for controlling PH, your existing test kit can test for PH and you'll add acid whenever the PH reaches about 8 targeting 7.4 or 7.5.

This is the fastest way to get your pool in a manageable condition so that you can enjoy the rest of the swim season.

Let us know if you have more questions.
 
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BPool5

Member
May 29, 2020
19
Illinois
Pool is almost drained. I will clean it and refill. Guy at pool store was telling me there’s a filter I can get at Home Depot for my hose so I don’t wind up with green water because I’m on a well. Every time I fill my pool it’s about 5 days of muratic acid before kids can swim. Anyone know what this filter is? I’m in Chicago area and we probably only have 4-5 weeks of swimming weather so don’t want to waste a week getting pool swimmable.