Please review plan

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Yip, thanks.

I already started raising CYA, by putting 64 ounces of stabilizer in two socks in the skimmer baskets. This is half the amount the Pool calculator showed was need to raise CYA from 20-40, per Kim's suggestion, but was all I could fit in the socks. So, I guess I am pretty much committed to this.When I brushed this morning, the black algae looked better than a day and a half ago. Weather was crappy here yesterday so I didn't brush, but it was encouraging to see the improvement, especially in areas where brushing is easier, it is working!

Question on the FC level to maintain.

For black algae, there is a recommendation to keep the FC between high end of range, and shock level.
At CYA 20, the pool math calculator shows shock level as 10
at CYA 30, the shock level is 12
at CYA 40, the shock level is 16

This is to your point about requiring more FC when CYA is higher.

For now, my target FC to combat this black algae is going to be 10. My guess is after the CYA settles in to the pool, my CYA will be around 30 (since I added ~ half the CYA needed to go from 20 to 40).

This FC level of 10 is between high end of range and shock level for CYA 30.

Agree?

Thanks so much - it is very rewarding to have some success winning against something that placed us all last season.
 
So, I already put 64 ounces of powder CYA in socks in the skimmer basket. Based on the pool math calculator, this is about half the amount needed to take CY from 20 to 40, per Kim's recommendation.

The black algae is going away slowly, but definitely going away. Weather is great this weekend, and I am going to brush 4 times per day.

As I understand it, I should keep FC between High End and Shock level.

For CYA 20, Shock is 10
For CYA 30, Shock is 12
For CYA 40, Shock is 16

My guess, based on the calculator, is my CYA is headed towards 30, with the powder added. So, my goal is to keep my FC around 10-12 until further notice.

Gonna brush often.

Sound good?
 
If you can take the FC up to shock level all this weekend, and maintain it there, I think it will go a long way towards fixing your algae. Especially if you're able to brush as often as you can.

Squeeze those CYA socks now and then to help speed the dissolving process. Milky white fluid will come out- harmless to you, just wash your hands after. Once all out of the socks retest that CYA.

How warm is your water? Its still pretty cold in MO, isn't it? I was surprised to see my pool water was 64 degrees today. Its a strange year, huh!?
Yip :flower:
 
Update on my situation. After brushing as much as I could, and maintaining FC between 10 and 12, 95% of the black algae is eradicated! Just a few remnants left!

Here are my updated chemical levels, and would appreciate any advice from here.

FC - 10
CC - 0.5
pH - near 8.0 or 8.2 - I then just added half gallon of Muriatic Acid, per pool calculator to bring to ~ 7.5 (Later Edit: I retested pH several hours after add the Muriatic, and it is 7.5! Wow, this is so rewarding!!!!)
TA - 130
CH - 375
CYA - 30 - this is what I expected after adding half the CYA needed by Pool Calculator to go from 20 to 40, so pretty cool!
Salt = 2,400, the SWG light is red for low salt
 
OH yeah... you've got this! And if your chemical additions brought you right where you expected, your pool volume is on the money. Good job!!

Keep the FC up and brush now and then and lets see if those last few splotches will disappear. :goodjob:

Yippee :flower:
 
Thanks Yip and Kim - Funny story on pool volume. I estimated based on length, width, a guess on depth, and taking into a count the odd shape. I estimated 40,000 gallons. I just found the original builder's manual here and looked through it, and saw a note about pool size, 39,200 gallons. Not bad!
 
Hi All,

The black algae is eradicated! There are a couple spots in a 90 degree corner in the deepest spot of the pool. They are the size of a nickel, and might even be something else. I am calling victory! Thank you all for your help! By they way, I bought a small 5 inch wire brush attachment from Leslie's, this is a must have for black algae, was able to do serious scrubbing with this small attachment.

Here are readings for today. I did a preliminary test four days ago, and pH was high, so I added Muriatic acid (note PH is high again). i also added one bag of solar salt. At this point, I am really interested in adding Borates before swim season. My only hesitation is dog drinking water with them in, but I am reading conflicting information. I will continue to research.

Can anyone suggest water levels to now get to before start of swim season?


Wednesday March 15, 5pm

FC - 3.5
CC - 0
pH - between 7.8 and 8.2
TA - 140
CYA - between 40 and 50, closer to 50.
Salt is 2,660

Wednesday, March 8th, 5pm

FC - 10
CC - 0.5
pH - near 8.0 or 8.2 - I then just added half gallon of Muriatic Acid, per pool calculator to bring to ~ 7.5 (Later Edit: I retested pH several hours after add the Muriatic, and it is 7.5! Wow, this is so rewarding!!!!)
TA - 130
CH - 375
CYA - 30 - this is what I expected after adding half the CYA needed by Pool Calculator to go from 20 to 40, so pretty cool!
Salt = 2,460, the SWG light is red for low salt
I also tested Bromine and Salt

Borate strip test is 0, as expected
Salt is 2,460
 
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Congratulations! That's great news :)

If it were mine, I'd assume 50 ppm CYA and keep the FC on the high side for a while. There's no downside, so I'd be using 5 ppm FC as a bare minimum for a while.

pH will rise very quickly with high TA, so I'd be reducing TA. It will come down slowly on it's own from the normal acid additions, and in any event I'd be keeping the water below 8.0

Before borates, you want to get your TA down to around 60 or 70 and your pH moving a bit more slowly. You can lower TA more quickly by correcting your pH to 7.0 or 7.2 each time you add acid. The fastest way to drop TA is to drop pH to 7.0 and then aerate aggressively to get a faster pH rise, followed by dropping pH to 7.0 again, then aerating again, then repeating as necessary until TA is down to where you want it. Here's the article describing this procedure: Pool School - Lower Total Alkalinity

Anything you can do to reduce top-ups with high TA water will be helpful long-term (for example rainwater from your roof if that sounds feasible). Your fill water tests seem odd with pH 7.2 and TA 240, so it might be worthwhile re-testing your top-up water. Let the tap run for a few minutes before drawing your sample.

I'm guessing your water is very cold, so the SWCG can be turned off until the water warms up.

You mentioned testing bromine. If there's no bromine history, you can ignore it.

Must feel great being rid of that black algae!!!
 
needsajet said:
Congratulations! That's great news :)

If it were mine, I'd assume 50 ppm CYA and keep the FC on the high side for a while. There's no downside, so I'd be using 5 ppm FC as a bare minimum for a while.

pH will rise very quickly with high TA, so I'd be reducing TA. It will come down slowly on it's own from the normal acid additions, and in any event I'd be keeping the water below 8.0

Before borates, you want to get your TA down to around 60 or 70 and your pH moving a bit more slowly. You can lower TA more quickly by correcting your pH to 7.0 or 7.2 each time you add acid. The fastest way to drop TA is to drop pH to 7.0 and then aerate aggressively to get a faster pH rise, followed by dropping pH to 7.0 again, then aerating again, then repeating as necessary until TA is down to where you want it. Here's the article describing this procedure: Pool School - Lower Total Alkalinity

Anything you can do to reduce top-ups with high TA water will be helpful long-term (for example rainwater from your roof if that sounds feasible). Your fill water tests seem odd with pH 7.2 and TA 240, so it might be worthwhile re-testing your top-up water. Let the tap run for a few minutes before drawing your sample.

I'm guessing your water is very cold, so the SWCG can be turned off until the water warms up.

You mentioned testing bromine. If there's no bromine history, you can ignore it.

Must feel great being rid of that black algae!!!
Click to expand...

Thank so much!!!

I will add MA to drop pH to 7, and keep chlorine higher (based on CYA of 50).

The Fill Water Test I did was on the outside spigot, after filing my hot tub, so it had run a good long while (which is similar to when I use it to fill my pool). We are on a well, with a nice water softening system, that even services the outside taps, but I too am concerned about the high TA fill water, as I will be battling this all the time (on hot tub fills, pool top offs, pool fills, etc...).

I have a dumb question about the SWG, and turning it off. It is an intellichlor iQ60. I don't see an on/off switch. The SWG is cabled into a sub panel type box that clearly has not been opened in a while. Do I just disconnect the cable at the subpoena, and more importantly, do I have to worry about any lines or anything freezing now (we have been in the 20's at night). I am running my pump 24/7 to avoid freezing. I understand the SWG is not producing FC at the low water temps, but is there any harm in letting it run? I have a long track record of making things much worse by trying to perfect things :)
 
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No worries, yeh, to turn it off, turn it down to zero % by pressing "less" until all 5 lights are out. No need to disconnect, and no harm leaving it at another % either.

And just to be clear, don't intentionally hold the pH at 7. Let it rise back up to 7.6 before dropping it again. Each time acid is added, it eliminates some TA. The pool water pH will rise from CO2 outgassing, giving the opportunity to drop it again, eliminating more TA.
 
needsajet said:
No worries, yeh, to turn it off, turn it down to zero % by pressing "less" until all 5 lights are out. No need to disconnect, and no harm leaving it at another % either.

And just to be clear, don't intentionally hold the pH at 7. Let it rise back up to 7.6 before dropping it again. Each time acid is added, it eliminates some TA. The pool water pH will rise from CO2 outgassing, giving the opportunity to drop it again, eliminating more TA.
Click to expand...

Yep, got it on not maintaining pH at 7. I am familiar with the TA reduction process from my hot tub I just got. It is just with the pool, I had to combat the black algae first. Now that this is tackled, we are able to move on to more permanent water balance and chemistry focus.

Follow on question, do I need to aggressively aerate the pool, since we won't be swimming in it for several weeks? I would think the pool would naturally aerate just from the returns and surface area exposure. I do have a water feature that I ran all day yesterday, but only reason I did that was to aerate.

Thanks for ALL the help.
 
No need to aerate aggressively and yes it will aerate from normal exposure of the water. Your water is well balanced, so there's no rush. TA is lowered to reduce the frequency of acid additions, and pH rise will be a bit slower right now anyway.

If you don't want to lower TA quickly, just let it rise to 7.6 then drop it to 7.2 between now and swim season and TA will come down gradually. If the TA hasn't come down enough closer to the time you want to add borates, you can use the faster TA reducing method. Same would apply if you top up the pool and the new water causes a TA rise.

You're very welcome, and ask anything anytime and Kim, or I or others will help you keep it going in the right direction for your plans.
 
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