Is grren always algae?

[vjpool]

I'm very new to this and my pool water is still light green. Yesterday, I vaccuumed, backwashed, rinsed and shocked. Results-light green, slightly cloudy water.
My readings this a.m.:
Hardness-250
TC-10+ (I will purchase the kit that reads higher-I believe it's higher because the color is much darker than the comparison on strip bottle)
FC-10+ (same explanation as for the TC)
pH-7.2
TA-80
CA-150

I went to the pool store to buy algacide but keep thinking from various posts here, that it might not help. Am I misreading something? Please help. Thanks.

[vjpool]

I forgot to mention that my pool is inground 16x32 gunite.

[Guest]

[Guest]

I woke up yesterday to a green tinge in my pebble tech 12000 gal pool. Come to find out the chorine frog was empty. I quickly went to the pool store and they had me get 2 bags of smart shock and of course some more chlorine. Since I could still see the bottom of the pool, they were sure it would solve the problem. By the end of the day my water was clear again. Maybe that will help you? Hopefully you have already solved your problem though since this was a few days ago.

From now on I am going use that particular shock when ever I need to shock it!

[vjpool]

On my original question, is green always algae? Also, what's the difference between shock and chlorine? Not to sound silly, but I thought they were the same.

[chem geek]

Green either indicates algae or copper precipitating out of solution (usually as copper hydroxide). If your pH went up, say from adding lots of chlorine or a pH Up product, then if you had copper in the water that can turn it green. The easiest way to tell is to see if you have chlorine demand (i.e. lose chlorine) overnight. With copper, you won't; with algae, you will and even daytime demand will be higher with algae.

You can also take a bucket of pool water with some of the green in it, partially cover it and leave it in the sun and if the green grows, it's algae. Algae will also feel slimy; copper won't.

You should have a good test kit, the Taylor K-2006, since the amount of chlorine you need to shock and kill all the algae (if that's what it is) is dependent on your CYA level. A full set of water chemistry numbers would be helpful to know.

[vjpool]

Thanks Chem Geek. I took a sample to a different pool store and got a more detailed reading. Here's what I have:
FC - 43.2
TC - 43.2
pH - 7.4
TH 200
TA- 75
CYA - 82
Copper - 0.06
Iron - 0
Tot Dis Solids - 990

I was told to add:
1) 13.2 lbs of Alk up
2) 4 lbs turbo shock
3) 25 oz of Resuce Concentrate Algaecide

They told me to add in this order and to add #'s 1&2 first, retest, then the next day to add the algaecide.

Does this sound about right and should there be some wait time between #1 and #2?
Thanks.

[chem geek]

I don't know how deep your pool is, but if it's an average of 4.5 feet (3 to 6 feet) then it's about 17,000 gallons.

Anyway, your water is very corrosive (to plaster/gunite/grout) because your pH, TA and CH are all low, but it's really the Calcium Hardness that you should raise to about 300 ppm. However, your CYA level is also high -- the first test implied 150 if that's what CA meant (not sure if that's CH or CYA) and the second test says 82. You CAN run your pool with a CYA of 82, but would need to not use stabilized chlorine and would have to keep your FC level at a target of 9.5 ppm and an absolute minimum of 6.2 ppm. The other alternative is to use a weekly algaecide, but that can get expensive (and if done, then the algaecide should be PolyQuat 60).

Also, if your chlorine level is really that high (43.2) then the pH will drop significantly as the FC level drops. I'm not sure how they got an accurate pH test with such a high FC level unless they used a meter instead of a color test (phenol red indicator). And I don't know why they are asking you to add turbo shock since your chlorine is already too high. Perhaps the turbo shock is Cal-Hypo and that will add calcium to the water which you need, but it also adds chlorine which you don't.

Don't add chlorine -- let the sun exposure reduce your high chlorine level. And get some calcium in your pool by adding Calcium Chloride. I'm surprised they didn't suggest that. That's about 24 pounds of anhydrous or 31 pounds of dihydrate Calcium Chloride. Of course, if you're going to do a partial drain/refill to lower your CYA level then you can add the calcium after doing so. Or you can add less than these amounts and use Cal-Hypo as your chlorine source.

I would not add any Alkalinity Up since you should use non-acidic sources of chlorine (bleach, chlorinating liquid, Cal-Hypo). I would get your pH Up using 20 Mule Team Borax or if you want to buy it at the pool store it's sold as Proteam Supreme (but is more expensive). As the chlorine gets broken down by sunlight, the pH will drop and you can add Borax to compensate. My guess is that it could take as much as 12 pounds of Borax as the chlorine drops to around 10 ppm FC, but I am not confident of these pool store numbers. Having your own test kit would be better for confirmation.

As for the copper, once your water is in balance you might not have a problem anymore, but if green remains then you can use a sequestrant to hold the copper. If you are going to be doing a partial drain/refill to reduce the CYA, then that will reduce the copper as well unless it's coming from your fill water. Have your fill water tested for everything so you can see what sort of TA, CH and copper you are adding to your pool.

I hope others can help you on this forum as well -- there are quite a few knowledgeable people here. The pool store doesn't seem to know what they are doing -- having you shock when they say you have 43 ppm FC borders on insanity.

[vjpool]

Dear Chem Geek - I questioned the readings also - one reason I didn't do anything until I spoke with this forum. My pool is 16x32 gunite-23k gallons. I took a reading this morning. Here are my numbers.

Hardnesss-250
TC - 12
FC -10
pH 7.2
TA - 90
CYA - 100

I guess I'll go back to Leslie's for a reading and NOT the pool store I used on yesterday. Also, I think I'll get that kit today. By the way, the algae continues .....

[vjpool]

I forgot to say that the shock the store recommened is Cal-Hypo.

[chem geek]

Well, with your very high CYA level it's going to take a LOT of chlorine to kill the algae. You'll need to get the FC level close to 40 ppm and keep it there. Since you'll probably want to lower your CYA level anyway, you could just start doing a partial drain/refill -- vacuuming out the algae along the way. You should have at least some chlorine in the water even if not at shock level, but when the CYA is diluted to, say, 50 ppm, then you'll only need about 20 ppm FC to shock for the algae and will only need about 5 ppm FC to maintain to keep algae away.

Your hardness is already at 250 ppm so you'll have to watch the Calcium Hardness level when using Cal-Hypo. For every 1 ppm FC added with Cal-Hypo you also add 0.7 ppm CH. Bleach or chlorinating liquid would be a more pure source of chlorine.

[Backglass]

Also, what's the difference between shock and chlorine? Not to sound silly, but I thought they were the same.

Shock isn't something you buy, it's something you do. You use chlorine to shock a pool....any kind. The bags you see called "shock" ARE for "shocking", but are just chlorine. It's marketing.

[vjpool]

After the posts this morning, I switched back to Leslie's for a reading....here's what I have:

FAC-5
TAC-5
pH-7.6
TA-90
CYA-60
TDS-800
Copper/Iron-0

Quite different from the other reading. I don't know what the other store's clerk was reading, but I'm glad my common sense said "not to do anything they told me".

Can you help me from here? My pool is 16x32 inground gunite, @20,000 gallons and, still green; although I vaccuumed and backwashed but did not add any chlorine since the readings indicated were so high. I just want blue water again!

Thanks.

[chem geek]

You really should get your own Taylor K-2006 test kit since I'm not sure whom you can really trust. The "5" chlorine level is suspicious because maybe Leslie's just used a DPD test that has a visual max of 5. If they used an actual colorimeter device, then perhaps the 5 is a real number.

With your own test kit, you will be able to measure the actual, real chlorine level frequently so as to maintain a high level during shocking. You can certainly add more chlorine assuming this latest pool store is correct, but please, please get your own test kit. Then shock with chlorine having the Free Chlorine (FC) up to 40% of the CYA level. Since knowing the CYA level is critical, your K-2006 test kit will give you that level (as well as chlorine and other parameters).