Starting to see algae in my new pool

[jetskierg]

I'll admit i have slacked off on brushing the pool in the last month because it is still record Dang heat, and I have this dermatology thing going on that i can't go in the sun, but i am surprised to see a little algae forming in the crease of the steps and on the love seat. How can i fix it before it gets worse? My FC & PH seem pretty decent and there is no CC. thx

todays numbers:
FC - 4
CC- 0
PH - 7.4
TA - 6 drops to pink color, kept putting in drops and it was still pink after 20 drops when i stopped. so 60-200?
CH - 410
CYA - below 30
CSI - 0 to 0.1 (water 78f) Pool math says it is - 0.2

 

[mknauss]

How are you chlorinating your pool? A really low CYA here in the desert usually means rapid burn off of chlorine.

Regardless, follow the SLAM Process

Your TA is 60. Once the sample goes to bright pink you are done.

 

[Dirk]

How sure are you of the 20K water volume number?
Did you ever put in any CYA? If so, how much?
"Below 30" could be anywhere from 0–30, as 30 is the lowest the K-2006 can test for.
Once you have completed the SLAM, you need to get your CYA up to a measurable level, so that you know how much you have. Then you can correctly calculate the correct FC level.

 

[jetskierg]

I use liquid chlorine 10% and MA 31%. Yes i put in the required stabilizer back when the pool was first refilled. So i guess i am going to slam. says 12 gallons. SLAM isn't clear to me on certain steps. So on the chart, am i looking at the CYA i have now (30) or the CYA i want to have (40) to see the FC level i need when slamming? Pool math states i need 12 gallons of chlorine. Do i put it in all at once? How much do i add at a time and how often if my FC is not at the target level for Slaming? It states to check at least 2x a day. How many times is normal?
So when the CYA gets to 40 and FC is 5-7, and the CC is below .5 and it passes the overnight test I am done? ( 'and can allow the FC to drift down to normal levels' ) Thanks for your patience, i am a newbie at this chemical stuff.
P.S mknauss- you are in the same misery we are, we are finally getting down to high 90's this week. Woohoo!

 

[Dirk]

Use your current CYA level for the SLAM. Do not raise CYA now, it'll just take more chlorine for the SLAM.
Chlorine all at once, yes, with pump running. Distribute it around the pool for faster mixing.

There is no normal for checking FC, even 2x a day is just a starting point. Every time your FC drops below SLAM level you risk increasing the number of days it's going to take. Test as often as needed (or as often as you can) to be sure you never slip below SLAM level. If you're at all below SLAM level after testing, you bring it right back up again. Keep plenty of chlorine on hand. Do not run out during a SLAM.

The end-of-SLAM criteria has nothing to do with CYA. Do not alter current CYA level before or during the SLAM.

Your FC needs to stay at SLAM level until the SLAM is done. So FC of 5-7 does not indicate end of SLAM.

You must pass ALL THREE end-of-SLAM criteria before declaring yourself done (before letting your FC drift back down). If you cheat, you'll likely get a resurge of algae and have to start all over again.

You are done when:

• CC is 0.5 or lower;
• You pass an Overnight Chlorine Loss Test
• And the water is clear.

 

[jklocke]

Pool math states i need 12 gallons of chlorine. Do i put it in all at once?

Double-check your PoolMath calculations. You might need 12 gallons for your whole SLAM, but you should only need 1.5 - 2 gallons of 10% liquid chorine to get from 4 to 12FC in a 20K pool.

 

[Dirk]

@jklocke, Jeff, good catch!

 

[jetskierg]

omg. thanks for that. don't know where i got 12 gallons from. lol. must have confused it with the FC number. So i am starting now. it is another 100 degree day. I'm putting in 1.5 - 2.0 gallons. So check again in an hr or so? or longer? Do i do the overnight test tonight? thx for the advice.

 

[Dirk]

Do the OCLT after you pass the other two criteria (CC and water clarity, which includes no visible signs of algae anywhere).

 

[jetskierg]

alright. So check again in an hr or so? 2 hrs? or longer? thx

 

[Dirk]

Do three hours and see where you're at. It sounds like you caught your algae early. If that's true, you won't have many tests to do. And as the chlorine does its job, you'll use less and less each time. And so can stretch the interval between testing each time.

If you're running low on reagents, you can fudge the FAS-DPD test (but only for a SLAM, and not every test, and not for the OCLT). Use a 5ml sample of pool water and a single scoop of the powder. 1 drop = 1 FC (so you'd want to get 12 drops for your SLAM level FC 12). This is a less accurate test, so be especially careful measuring out the 5ml sample.

 

[jetskierg]

tested at 3.5 hrs. FC at 7 now, (after adding 1.75 gal) CC very light pink so .5 (it was clear before i started SLAM and at 0)
I just added 2.5 gal chlorine. Will check again later. Do I have to get up in the middle of the night to add chlorine? It seems that i would to keep it at an elevated level, although no sun absorption at night.

 

[Dirk]

Up to you. As I said, every time it slips below SLAM level it could extend the length of the SLAM. Are you trying to preserve any swim season? Might be worth getting the SLAM over as soon as possible. If not, then don't lose sleep over it, literally!

The SLAM is working. A loss of FC 5 in 3 hours is significant. The chlorine is chewing on something, and the CC is the byproduct.

@mknauss: Marty, we know it doesn't help to go over SLAM level during the day, as the excess chlorine will just burn off in the sun. But can he goose his FC just before bed, to say 14 or 15, to make it through the night? (His SLAM level is 12.) Or will that just be wasted, too?

 

[jetskierg]

It wasn't a loss at all. (was FC 4 in the beginning) I just tested again after 3 hrs. FC - 14 and CC just barely very faint pink, so one drop turned it clear. so .5

 

[Dirk]

There's something wrong with your math, or the way you're slamming or reporting what you're doing. You were supposed to bring the FC up to 12. That's your SLAM FC level based on your CYA of 30. So if after 3.5 hours your FC was 7, that's a loss of 5. What am I missing?

Anyway, if your FC is currently 14, then that's fine. But try to keep it at 12.

 

[mknauss]

But can he goose his FC just before bed, to say 14 or 15, to make it through the night?

I suppose you can. We do not like to see members going above SLAM level FC as that makes the active chlorine higher than we feel is safe for swimming.

 

[jetskierg]

Before slam my FC was 4 and CYA was 30. Then it went to 7 when tested 3hrs after beginning SLAM and adding 1.75 gal chlorine. Obviously FC was not high enough so i added 2.5 gal chlorine and it went to 14. I have not gone down on FC at all. It was never at 12.
I will not be swimming anytime in the near future.

 

[Dirk]

OK, well we are not communicating well enough here. And you don't seem to be understanding what a SLAM is, or how to start one, or perhaps how to calculate FC dosing. So let's back up.

1. What is the strength of your chlorine (percent)?

2. How, exactly, are you determining how much chlorine to add?

If you're confident you're at FC 14 now, then you're probably fine for tonight. I won't be able to help you tomorrow, but others can, if you can answer those two questions.

 

[jetskierg]

Agreed. so i woke up this morning and looked at it a different way. You are saying when I saw it was just 7, and added more chlorine to try to get to 12, I should have tested again immediately. I should not have waited 3 hrs to retest that. I misunderstood. At any rate, i just tested (830am) and FC is still at 13 (stayed up overnight) and CC is faintly pink so i guess it is still .5

1. liquid chlorine 10%
2. I think pool math stated to add between 1.5 - 2 gallons to start so i put in 1.75. That only got me to FC of 7.(which was up just 3) I don't remember what pool math said after that. I think it was only to add a gallon or gallon and a half, and i knew that wouldn't get me to twelve as it only rose 3 points with 1.75 gallon previously. so next time i put in 2.5 gallons to try to hit 12. It got me to 14.

So I guess my job is to make sure it stays at FC 12 today and brush the pool. I am running low on the main reagent so will have to go find some today.
thanks for everyone's input.

 

[Dirk]

OK, so... not sure where you're getting a range of chlorine (1.5 - 2)?

Try this if you want to do this right: use the web page version of Pool Math.

Start at the bottom of the table and select the appropriate choices from the popup menus in the section labeled "Suggested Goal Levels:"
"troublefreepool.com:, "bleach" and "plaster."

Then go back to the top of the table and fill in your pool's water volume number in the "Size" section.

Test your water for FC and put that result into the left-most field of the "FC" section. Put "12" into the field just to the right of that one.

Still in the yellow "FC" section, in the right-most cell, put "10" into the "%" field, and select your chlorine's container size from the "Jug size" popup menu.

After you do all that, stay in that same yellow table cell, in its top-left corner, will be the exact amount of 10% chlorine to dose into your pool, to elevate the FC level from what you currently have to FC 12. Then you go pour in that amount, with the pump running. Within 30 minutes, your pool will be at FC 12.

Some number of hours later, repeat that exact same process to keep your pool at FC 12. Maintain FC 12, using the same process, until you can pass all three of the end-of-SLAM criteria. That might be later today, or a week from now.

If you haven't been doing that, just like that, then you haven't been SLAMing your pool. (Though, if you were at 14 last night, and 13 this morning, that counts.)