SLAM worked, I think... Need confirmation

[GloveAsh]

Hi - I just found this forum after having to take over care of our pool from the pool service. Long story short, this summer our pool started to get a continuous mild case of green algae despite having a weekly pool service. This is a big deal in Texas when the only thing you can do with your kids on a blazing hot day is throw them in the pool. The service couldn't fix it for over a month, so I fired them. My husband started trying to balance the pool, and despite his best efforts, it kept going back to green after a week or 2 of clear. Finally we called in someone who diagnosed a couple of suction leaks in the pipes which kept the filter from really clearing the pool. This was repaired 2 weeks ago. By then we had a totally dark green, algae filled pool. At this point, spouse was down from some surgery and I was on my own to clear it out. This is where your forum came in pretty handy. I have been using the SLAM method on the pool in a pretty disciplined manner - brushing daily, testing 2 times a day, backwashing frequently. I even did 3 clean outs of our filter in the first week and added back DE each time. This all paid off as we now have a clear pool - so thank you guys. My new Taylor testing kit came in the mail last week and I started getting better data than our Leslie's pool strips.

2 questions now:
Question 1) The pool is clear, but I am still losing chlorine over a 2 day period. I added chorine to shock level 2 days ago and right now the levels are:
2.8 FC
0.2 CC
7.4 Ph
50 ppm TA
245 ppm CH
80 ppm CyA

Based on what I have seen, the chlorine will be gone tomorrow. The chorine loss is slowing down, but still happening. Am I still in SLAM mode? Or is this a different phase?

Question 2) I think I need to tackle raising the Alkalinity now as it has been low throughout this process. I ordered baking soda. I also see that the CyA is high. Does the Cya level matter? The Taylor "table" says to add 12.6 lbs of baking soda to our 30K gallon pool to raise it 30 ppm. I am planning to do this today and want guidance that I am headed down the right path. Also, should I had half the baking soda now, and half later, in case it doesn't take that much?

Thanks in advance for the advice. I love my newly clear pool and don't want to lose momentum!

 

[otter86753]

Welcome!

Question 1 For a CYA of 80 the minimum FC level is 6 on a non-SWG pool per this chart Pool School - Chlorine / CYA Chart
You may have a nascent algae outbreak which is why you are losing your FC. I would boost the FC level to 10 and perform an OCLT Pool School - Perform the Overnight FC Loss Test (OCLT) to rule out a nascent algae bloom.

Question 2 Your CYA level of 80 is high for a nonSWG pool and will require more chlorine for daily maintenance or a SLAM. Regarding your TA, some pools like a lower TA as it keeps the PH more stable. It is unique to each pool and you may want to get your CYA in control first before tackling the TA. Once you have the CYA in order, you can see what your pool likes/needs to keep a healthy CSI (found at the bottom of PoolMath). Others may have a different opinion, but that is how I would tackle your issues.

Good luck and ask all the questions you need/want.

 

[GloveAsh]

UGH. I was worried that someone would tell me to hit the CyA first. I didn't feel like draining 25-30% of the pool after everything else that has happened in the last few weeks. Oh well - looks like a good excuse to do a final post-SLAM filter clean as well.

 

[Divin Dave]

Lots of folks have maintained their pool with higher than recommended CYA. The trick is to not let it get any higher, which means not using trichlor pucks. Use only liquid chlorine sources.

Over time, with dilution by rain and backwashing, the CYA will slowly come down to a better level.
Just be sure to maintain your FC/ CYA relationship which otter provided a link to the chart.

There are 3 criteria for completing the SLAM.
your CC is .5 or less
your water is clear
you pass the OCLT.

If you dont meet all 3 of these, then you need to continue to SLAM until you do.

Its at the end of the SLAM where most people falter. You need to be more than 'see the bottom' of the pool. The water needs to be clear, as in crystal clear, and pass the OCLT before you let the FC come back down to maintanence level.

UGH. I was worried that someone would tell me to hit the CyA first. I didn't feel like draining 25-30% of the pool after everything else that has happened in the last few weeks. Oh well - looks like a good excuse to do a final post-SLAM filter clean as well.

 

[MarianParoo]

Your signature says you have a SWG. Do you? If so, your recommended CYA is 70-80 and you shouldn't have to drain and lower it. I am a bit confused.

Also, I suggest that you use a 10ml sample for FC/CC tests. Multiply your drops by 0.5.

 

[duraleigh]

Am I still in SLAM mode? Or is this a different phase?

You never correctly completed the SLAM. Please reread the article....the SLAM is complete when...

1. Your pool water is sparkling and there is no visible algae (dead or alive)
2. Your CC's are .5ppm or less
3. You can hold your FC overnight without losing more than 1ppm.