Milky light green water after storm

[bobjdan]

Yesterday my water and pool looked fine and my chlorine level was at 2 ppm in the a.m.. I added enough bleach to get it to around 5 (CYA 50). Early this a.m. we had some thunderstorms and a hard 3-4 inches of rain in a few hours. It came down so hard that the water was coming in faster than my overflow could get rid of it and I had to backwash some out.

The water looks like an off color light milky green which would seem to indicate an algae bloom. However when I tested the chlorine it was still at a 2 which seems strange for an algae bloom. So I put on my goggles to see what was going on and it seems like there is a thin coating of something on the walls and bottom of the pool. Whenever I've had algae before, I've never seen it happen overnight like that, I usually see it as patches of algae starting in the deep end. It does look a bit like a few times I've taken the cover off and seen a similar the color only it's not not nearly as dark of a green.

So it would seem like it is some sort of algae bloom, but if so, why was there still FC of 2. combined chlorine of .5 or less. The worst part is that I have a pool party this afternoon so I don't want to start a shock routine until tomorrow. Is there something that could have come down other than algae to cause this that anyone knows of. Should I at least shock it assuming it once since it should still be safe to swim in?

 

[Patrick_B]

You are in the beginning of an Algae bloom if not already well started. You haven't had enough FC with 2.0 and your CYA level of 50. Sorry, but you need to shock and complete the whole process. I know that isn't what you want to hear, but Im afraid its the case. I would not say safe to swim either. I will go in with high FC, but not slimy and or green. Really sorry to rain on ya.

 

[woodyp]

Adjust PH down to low end and shock. The sooner, the better, the quicker you get it back in use. Use the chlorine/cya chart in pool school for shock level and adjust your FC higher when you're done accordingly.

 

[frogabog]

With a CYA of 50, your minimum is 4ppm, and you should target 8ppm to get you through each day without falling below 4ppm.

Shock level is 18ppm, which must be maintained throughout the process. Green water is as good a sign as to the need to shock as any, it will only get greener if you don't. The minimum and maximum per CYA levels are not enough to handle the bloom and will be impossible to maintain while algae is alive so if you let people in the pool today you will be completely out of chlorine very soon.

What kind of test kit are you using?

 

[bobjdan]

Thanks for all the suggestions. I use the TFT-100 and have been using the TFP method for the last 3 years with miimal problems. I'm especially impressed with how little I've had to adjust the PH or shock the pool.

I don't know if it was the light or what but after I wrote my initial post the sun came out and the pool no longer looks green, just bluish (the color of my liner and cloudy, just like I've seen after a bunch of kids have been in the pool all day and roiling up the water when the chlorine wasn't probably high enough. I also have seen it cloudy before I started following the recommendations of this site.

I think I have not been keeping my chlorine high enough to account for the loss from the sun which seems to be worse than usual this year, probably because of all the 95-105 degrees so the suggestion to get it to 8 in the a.m. to allow for the loss is a good idea.

After I wrote the post I decided to add a 182 oz. jug of chlorine just to get the level back to about 5.5 (that was before I read about starting it at 8). I just checked the chlorine and it is still at 4.5 so I'm thinking I don't have an algae problem or wouldn't the chlorine have been gone? I think the water just got beat to death and a lot of stuff settled in the pool, kind of like raining cats and dogs! I've lived here for 34 years and that is the hardest I've ever seen it rain for that length of time. Most of the mulch on my garden paths has been redistributed, some of it even to the neighbors.

My daughter has been having a party at my house every year for some of her college friends and this year is the 25th one. So they are all here now and the kids are in the pool. Once everyone leaves tonight I'll shock the pool, let it run all night and see if it starts clearing up tomorrow.

Thanks for the help and when my credit card billing cycle starts over next week I will make a contribution to the site.

 

[bobjdan]

It seems that you were all correct about an algae bloom but it is so much different than I'd seen before. I shocked to about 18 last night after dark and let it run all night. This morning the chlorine was down 3 ppm and I could see the white pool drain cover that I couldn't see yesterday. What was strange is that while brushing the pool I didn't see anything coming off the bottom and when I was done I could still see the pool drain. I topped it off this a.m. around 7:30 and by 10:30 it was down about 1.5 ppm, some of which may have been sun. The water looks milky but no evidence of green so I'm going to check it later this afternoon and again this evening, adjust as necessary, and see how it is in the a.m..

I did miss the part of lowering my 7.5 PH to 7.2-7.3 and now it is around 8. I read that it would go up so should I wait to the chlorine level is back to normal before adjusting it?

One other item that I'm curious about. A few weeks ago I noticed that my chlorine test tube had some black spots on the inside near the top. I couldn't rub them away with my finger so I filled it with bleach and let it sit for a few hours and that cleaned it up. It returned again earlier last week, I cleaned it again Friday and it was back again today. The only thing I could think of is black algae, but if it can survive 100% chlorine for a few hours I'd hate to see it in my pool. Before I had my problem yesterday I saw no evidence of any black spots in my pool--and hope I never do!

Has anyone seen anything like that (I couldn't find anything using several different searches). Do I need to get a new test tube? Does leaving chlorine in the tube for a few hours invalidate future chlorine readings?

Thanks.

 

[Bama Rambler]

Don't worry about the pH when the FC is high. The test is unreliable at high FC.

The black in your chlorine test vial is common. That's why there's a special vial in the TF test kits. Strong bleach is the fix, as you found. Rinse your vial several times after the cleaning.

 

[bobjdan]

My pool is almost clear now, but I can't seem to get the last of the algae indicated by the overnight test which dropped 3.5 ppm overnight last night even though I thought I had been following the shock procedure. Monday I had been checking it every 1/2 hour and then every hour and at times it didn't lose any in an hour. Then it lost 3 ppm overnight. Yesterday a.m. about 6:30 a.m. I added enough to get it back to shock level and by 10:30 it hadn't lost any so I let it go until 5:30 when the sun was gone and it had lost 4.5 ppm, some of which I'm sure was from the hot sun. I brought it back up to shock (16) and checked it at 9 pm and it was at 16 (what the pool calculator says it should be for 45 or 55 CYA level. Earlier yesterday I strained my water through a coffee filter and rechecked the CYA and it may be closer to 45 than 50. I wish there was a more objective test for that. Is what they use at the pool places any more accurate? Is there anything other than algae that eats chlorine? I've been brushing the pool daily and I vacuumed it this a.m.. It seems strange that there didn't seem to be any dead algae on the bottom at all and I wondered why I bothered to vacuum it. Seems like when I've had algae before that there was always dead stuff on the bottom.

My daughter from CA, boyfriend and 2 kids are here until next Tuesday and my other daughter's kids will be here as well the next few days as well so I won't be able to shock until they leave. It will be interesting to see what happens to the pool. If I have to start over I'll have to start over when they leave unless it gets really bad again. In the interim though, any thoughts are appreciated.

 

[Bama Rambler]

Raise the FC about 3 or 4 ppm above the PC's recommended shock level today and run it again tonight and see what happens. They can swim up to shock level so you'll be fine tomorrow.

 

[bobjdan]

I upped the Chlorine to 20 ppm about 4:30PM yesterday when the sun was mostly off the pool. It dropped to 17 overnight. The pool is probably about 95% clear now. It will be interesting to see what happens at normal chlorine levels. I'm not too excited about having to add close to 2 182 oz jugs of chlorine everyday, but it will also be interesting to see how much it loses overnight and during the day with the chlorine at normal levels which it should be at by tomorrow.

Any thoughts appreciated.
Thanks.

 

[Bama Rambler]

Is there a reason you've stopped shocking before you passed the OCLT? All the progress you've made will be lost if you stop now.

 

[bobjdan]

Shocking to 20 didn't seem to help and since it is above the normal shock level I didn't think it was a good idea to swim it. I probably got that from a previous response but after I reread it I now see it was talking about swimming in the algae and not the high FC level.

So at what shock level is it safe to swim in then?

 

[Bama Rambler]

Normal shock level is safe to swim in. With a CYA of 50 your safe to 20 ppm or so.

 

[bobjdan]

Ok I brought it back up to 20. I'll have to go get some more chlorine tomorrow and I also had to order some more stuff from tftest especially R-0871. Doesn't anybody have an idea of what kind of algae eats so much chlorine without showing any traces of anything being killed?

 

[linen]

Ok I brought it back up to 20. I'll have to go get some more chlorine tomorrow and I also had to order some more stuff from tftest especially R-0871. Doesn't anybody have an idea of what kind of algae eats so much chlorine without showing any traces of anything being killed?

Have you had to backwash? Eventually that is where the by products go, unless they accumulate on the floor.

 

[bobjdan]

I back washed it yesterday but I didn't really need to. Unfortunately my pressure gauge has been reading really high even after it has been backwashed for quite awhile and I've been too lazy to go to the pool store to get a new one. However the water pressure from the return lines was still very high, probably because I had had to backwash it Saturday a.m. after the storm to get some of the water out of the pool. It had rained so hard that the water was over the top of the overflow tube and almost up to the top of the liner. I had never seen that happen before. I'm glad I was home and not of town.

I'll go to the pool store tomorrow to get a new gauge and have my water checked. I'm curious to say what they read for CYA. In the past we have been very close to each other.

Thanks.

 

[bobjdan]

My grandson came in with burning red eyes after swimming in the pool at a 20 level. From what I have read that is caused by too high or low PH level. I've also read that PH levels are unreliable at shock level so what should I do? I assume the eyes will be ok after he sleeps? Should I try lowering the Ph some with Muratic Acid until I no longer need to shock?

 

[linen]

My grandson came in with burning red eyes after swimming in the pool at a 20 level. From what I have read that is caused by too high or low PH level. I've also read that PH levels are unreliable at shock level so what should I do? I assume the eyes will be ok after he sleeps? Should I try lowering the Ph some with Muratic Acid until I no longer need to shock?

The high FC level shouldn't cause the irritation (unless your CYA is quite a bit below what you have listed). Most likely it is the ph or CC. Do you know what your ph was the last time your fc was below 10 ppm? CC can cause irritation, so if you find that you have it, that may be the problem.

I would guess his eyes should be fine in the morning.

 

[Bama Rambler]

I'd let the FC come back down to about 10 and test and adjust the pH. That should take care of the problem. However, if the FC is killing algae, it's creating byproducts, which are irritating to the eyes, and that may be the problem. I'd recommend getting them some goggles while swimming.

 

[bobjdan]

Before I had the problem my Ph was around 74-75 range and has been all summer. I went to the drugstore last night and got some kind of otc Gel recommended by the pharmacist and he was fine this morning. It was pretty bad last night.

So when I checked the pool at 6:30 this a.m. my FC was 16 (21 last night at 8 pm) and CC was 0. I went to the pool place today at about 10:30 and he said my CYA was 10, my chlorine 8, and my PH 7.5. So I just got done checking my pool at 1:15 and it read FC 14, ph 7.5 and CYA 30! My wife got the same CYA reading. The other day when I checked it after straining it through a coffee-filter my best guess was around 45 but absolutely not below 40 so I'm confused. The only difference I can think of is that I had added about 1.5 inches to the pool on Wednesday and I had used a new unopened bottle of R-0013. The previous bottle had been opened in April or May for a test, then last Saturday, and earlier this week.

I hadn't noticed or had forgotten that the TF-100 test kit says to keep your test kit out of the sun, heat, and rain. Well it's sat outside all summer but only gets a bit of sun in early evening but there have been many days over 90, in fact it seems like most of them. Both the old and new bottles of R-0013 have been in the same place all summer. Does the heat change the chemical properties of any of the tests giving incorrect results? I have some new bottles of R-0013 and R-0871 coming probably tomorrow.

With my CYA at 30 the calculator says that for shock it should be at 13 so I guess that is why my grandsons eyes were burning at 21. I tried for 20 and measured the chlorine so my pool must be a bit short of 25000 galllons. Then again that's like a rounding error. So what level do you think I should keep the chlorine at until the algae is gone? 16?

Regarding the CYA I don't plan to do anything about it until we go on vacation for 6 days in a short while. Then I'll be filling my chlorinator with those 3 inch hockey pucks which should bring it up some and I'll check it then and see what it is. I remember seeing somewhere at this site how much those things raise CYA.

Thanks.

T