Opened pool to find a deep green surprise!

[Reebs]

Hi Everyone,

Great to be back on TFP for another season!

Not sure if this belongs in Testing and Balancing Water or where I put it in Algae- prevention and Treatment- I'd argue both. We took the cover off the pool last night to a big surprise. This is our 16th year with our pool and while every start to the season we take the cover off to a dirty pool, the water is usually not too bad. You can see the bottom fine and can tell there are 1000 worms, but generally the water is fairly clear and you can at least tell we have a light blue liner. Not the case this year! We were shocked to see it deep green. Our "pool guy" who we have used since the beginning to open and close our pool each year thought maybe a more mild winter was the cause, but that has happened occasionally in years past and this hasn't happened...anyway...the pool was green for the first time. After just a few hours (after getting us up and running) the pool water started showing signs of improvement. Before and After pictures are attached. The "before" was the deep green today at 2:00 when he got here and the "after" about 2.5 hours after he left.

To get my baseline after he left, I tested the water around 5:00PM and I was very surprised at how low the FC was given he just added a ton of liquid chlorine (I have a message in to him to try and find out just how much he added and clearly he did add it for the relatively quick results, but why would FC drop so fast? Test Results are here:

FC: 1
CC: .5
PH: 7.3 (always a little low for me at startup)
TA: 60 (always low at startup)
CYA: 0 (I expected it to be low with all the rain/snow all winter)

What stands out to me is FC only 1. Is it possible algae would eat through the chlorine he added that fast? I know there is no stabilizer in the water, but I would think FC would be much higher than 1 unless that;s just too much algae to "stay around". I was also stunned to see CC at only .5. I almost recorded it as zero because it didn't turn a slight shade of pink for a a few seconds after 5 drops. It very well could have been 0. Prior to testing, I was preparing to go through the SLAM process (something I really haven't done before). These results make me think I just need to brush/vac and backwash and add more bleach and stay after that cycle until the water is clear and NOT SLAM? Agree?

Also, how much stabilizer should I add at this stage? I know it is typically suggested to be around 60-70 for a salt water pool, but what about to begin the season here in my situation with my current test results? I have added no chemicals so far and will test tomorrow morning. My guess is the FC will be zero and maybe the CC will be up?? If that happens I will post back because that might require a different course of direction? Advice with my current situation?

Thank you!

 

[IceShadow]

Start with adding enough lIquid FC to get to 10ppm, mix for 30 mins, test again. Let us know what it is.

There’s a bacteria that eats CYA and turns it into ammonia, which takes a lot of FC to get rid of (and then the FC will kill the bacteria). You may not have this but seeing how quickly your FC drops will be the way to tell.

 

[Reebs]

Thank you for the reply. I tested the pool water this AM just to get basic results from over night. The pool water was largely unchanged from the "after" pic in the photos posted previously. The filter pressure gauge was more than 50% full (as expected). Test results were:

FC: .5 (barely turned the slightest shade of pink, probably closer to 0)
CC: .5

Then I did what you suggested and added 2 gallons + 1 Qt (288oz) of 10% bleach. I waited 30 mins and these were my results

FC: 6.5
CC: 1

Not sure why the CC would increase, but maybe there was so little chlorine of any kind that this mornings test was not really accurate??

I am going to backwash shortly in hopes to start clearing the water up, but the question is what else do I add/do. Should I keep the FC around 10 and keep after the back washing? Also, regarding CYA being 0, I checked what it was at closing last September and it was VERY low at 25. With all the rain/snow from winter and lowering of the water level a few times because of the rain/snow and increased water level, I am not at all surprised for it to have read 0 last night since it would have been diluted so much over the winter and was only 25 last fall. I only have 1 gallon of liquid stabilizer on hand. I assume I should at the very least add that now. Even that alone will not put very much in (I think about 16ppm). I will try and pick up more...question is how high do I take the CYA with my current situation? Thanks!

 

[woodyp]

You should take the CYA to 30 to help it hold some FC from the sun while slamming, and your SLAM level will be twelve.

 

[IceShadow]

OK - you have some FC still so dropping it from 10 down to 6.5 means it's not ammonia, which is good. You're clear to add the CYA and start dissolving it in the pool. We recommend taking something porous (like an old tube sock, nylon stocking, mesh bag you don't care about, etc.) and putting the granular CYA in there, then suspending it in front of a return jet to dissolve. Every so often stop by and squeeze it and let the CYA work into the pool. It took me about 24-30 hours to dissolve 5 lbs of it in my pool a few days ago. Once it's completely dissolved, you can wait about 24 hours and re-test the CYA level to get a reading. Until then, you can assume your CYA is 30 for the purposes of the SLAM even if it's still dissolving.

CC increases because the FC combines with the stuff in your pool. It will drop again when the FC breaks it up. For now you just need to worry about your FC and getting the SLAM going. As woodyp mentioned, you want your SLAM level to be 12. You want to check your pool FC level at LEAST 3 times a day, up to once every 30 minutes, and just add enough FC to get your FC level back up to 12 each time. Keep your pump running continuously during the SLAM. Brush and vacuum often - try to get everything out of the pool you can. Make sure to brush around the skimmer throat, behind lights that are removable, ladders/steps, etc. to get everywhere algae can hide.

Once your FC starts to hold between checks and your pool is no longer green, let us know and we can help with next steps. And please take photos and share every so often because we like seeing the green go away.

 

[IceShadow]

Sorry, just saw you mentioned liquid stabilizer. 1 gallon in your size pool will increase CYA by 16 (per pool math). I'd recommend adding that, waiting 30 minutes, and testing the CYA again - maybe you had some in there and it was less than 30 so it couldn't measure. If still too low you're going to want to add another gallon, or enough solid for it to raise another 15ppm or so.

 

[Reebs]

Thanks for all the help!! I just went out and got more CYA. All they had was the granular kind which I have never used before. I bought a 7lb bag to go along with my liquid stabilizer on hand (again just 1 gal for now). I suppose I will add the liquid stabilizer (instant conditioner) to get something more immediate in there and do the math and add the balance of the granular CYA to get me around 30 CYA. Thanks for the help...Will keep you posted!

 

[IceShadow]

Sounds good. Even if you have ~20 ppm in there and it's not testing because of that, you'd only end up at 50, which is manageable. (It might slow down the SLAM until you figure this out, but it's still doable.)

Get the CYA going and add enough to get the FC to 12, and start killing that green stuff!

 

[Reebs]

Good point- Thank you! Still a ways to go, but progress is being made (I haven’t been able to even vacuum yet but the water is much more blue than green now). I’ll report back in the morning. Will test at least once more tonight and add chlorine as needed.

 

[IceShadow]

Photos of the water are how we follow along. Please post if you feel comfortable!

 

[Reebs]

I sure will. If it wasn’t dark I’d go get a photo now. Quick update: I brought the pool to “slam“ level (target FC =12) around 3:00PM. Added the CYA then too. That was all right after backwashing. At that time, the water was a bit more clear in the shallow end (still very murky) but I was still was nowhere near able to see the bottom of the deep end. I then brushed a fair amount of the pool where there was still visible green areas to get that algae lifted into the new shocked water. I tested the pool water at 8:00PM and I expected there to be chlorine but largely reduced. Interestingply, FC had only dropped by 1 down to 11 After 5 hours. CC was still .5. The water Pool was looking more blue throughout but very cloudy (more than before I brushed which makes sense as a lot was “disturbed“ by brushing 5 hours earlier). I brought FC from 11 back up to 12. The filter gauge was also showing a significant increase in pressure so it’s working hard to filter out the garbage. I will post another update in the AM and a photo.

 

[Reebs]

Hello

Quick Update...Test results this AM after bringing the pool to "SLAM" levels (FC = 12) at 8:00PM last night were:
FC: 6.5
CC: .5
Water is still quite cloudy
Filter was full

I back-washed and brought the pool back to SLAM level of FC =12 this morning and will stay after it today. Its raining now and heavy rain is expected tonight and tomorrow morning so I will likely have to bring my CYA back up to 30 this weekend. I attached 2 photos to show progress and one from the same vantage point as the others above for comparison. I think that's pretty good progress after only about 40 hours apart? The other photo is for a closer perspective. There is still some shadowing and you can't see the bottom (deep end main drains would normally be very visible from here and you can see the haze start to show on the bottom pool step. Hopefully another day of filtering will improve it! Will post again on progress until there are no more issues. THANKS for all the help!

 

[IceShadow]

Filtering can take the longest. You have a DE filter so you'll need to clear it quite often, but it will clear up quicker than a sand filter would clear.

Unless you get a ton of rain, the rain likely won't make an appreciable difference in your CYA level. Over time a lot of rain could, but if you think about it, 2-3" of rain is a several hour deluge and still doesn't get close to any large percentage of a 48" - 96" deep pool.

 

[Reebs]

OK- very good and good to know! Assuming I stay after "SLAM" until I pass the SLAM requirements, is that when I look to start balancing the water (specifically to increasing CYA to higher than 30)?

 

[IceShadow]

Stay with the SLAM level and only measure FC until the water is clear. Once the water is clear (no visible signs of algae) do an OCLT - test FC after sundown, add to get to 12 PPM, do one more test after half an hour to confirm what the level is, then test in the morning before sunup to see if you've lost any FC overnight. Do the CC test as well to see if you have any CC. If you have 1 or less on your CC, pass the OLCT, and no visible algae, SLAM is done. Then you can add the CYA to get where it should be for your SWG, and get that going and running to maintain FC levels.

 

[Reebs]

Perfect- thanks for the advice and help!

 

[Reebs]

Quick update. This AM FC only dropped from 12 to 11 over night. I brought it back to 12. Filter was full again- Backwashed. Then after about 7 hours during the daytime it only dropped from 12 to 10.5. Water is slowly clearing. Filter not filling as quick Now. CC is still .5 both tests today but progress is made and I have only brushed the pool and have not vacuumed yet. Will tomorrow. I imagine that will really push it forward for the better. I can see the shallow end pretty clearly and can finally see the deep end drains late afternoon today (pics below). Very pleased with the progress in 72 hours. Getting there. Thank you!

 

[Reebs]

Update: I think I am ready to leave Slam mode as it seems all is pretty close to right with the pool again! What a difference a week makes! FC levels have not dropped dramatically at all over the last several days. Pool has been brushed and thoroughly vacuumed and the water has been very clear since Saturday morning. I brought FC to 12 Sunday morning and it only fell to 10.5 by 9:00PM after a very sunny day and the SWG off all day). I brought the pool up to SLAM level last night (FC=12) and this morning FC was 11. CC is .5. Filter pressure gauge barely increased after the last vacuuming (only up 1 lb from a clean start). Would you agree I am good to finish SLAM and focus on "normal" water test levels (and bring CYA up now)? Pics from a short while ago are below (deep end drains are very visible and have been all weekend. Thanks again for all the help.

 

[IceShadow]

Requisites for ending a SLAM:

- Pool is perfectly clear with no signs of algae (should be good by your post)
- OCLT passed (loss of 1ppm or less overnight) - check
- CC is 0.5ppm or lower - check

Looks like you're set to me!

 

[Reebs]

Would you take CYA to 60-70 right away? I plan to turn on the SWG and bring salt to 3500, but I know from past experience when the water is cold (currently about 58 with some cold nights coming up) the SWG doesn't always produce chlorine like it does when the water is warmer.