Not seeing much progress after 3 days of a SLAM

[al27]

After completing 3 days of a SLAM, I'm not seeing much progress. When we opened up the pool 6 days ago, the water was extremely green, but the green went away after running the pump for several days before starting the SLAM, even though I didn't add much chlorine during that time. When I finally started the SLAM, the water was blue but extremely cloudy. I could see the first step, could barely see the second step, and couldn't see the returns. The water looks pretty much the same as it did 3 days ago, but the second step is a tad bit easier to see and I can barely make out where the returns are now. I have been brushing twice daily and backwashing when filter pressure goes up 25% (I've only needed to backwash once in 3 days. Sand is only 2 years old). I haven't vacuumed yet because I'm worried that there could be some debris down there that we cannot see. We don't have a robot that we can throw into the pool. (Our pool is surrounded by trees so we normally get leaves in our pool over the winter, even though it is covered.) We have blindly netted the pool several times though so I don't think there is much debris down there. I've been using 10% liquid chlorine with a April 10th date and have been adding enough chlorine to get it up to 12 ppms using the pool math calculator. I've been testing/adding chlorine every 3 hours during the day and add the last dose when the sun goes down at about 8 PM.

When I woke up this morning at 7 AM, I tested the water and here were the results:
FC: 9
CC .5
PH 7.6-7.8
TA 50
CYA 30-35 (can barely make out dot at 35, dot disappears completely at 30).

Based on there results and what I've been doing during the SLAM, does anyone have any suggestions for me on what else I could do to get this pool to clear up? Is it possible that CYA is 35 since I can barely make out the dot at 35 so I need to be increasing the FC to 14 instead of 12? Should I decrease the PH or increase the TA or is it possible that the PH/TA is inaccurate since FC was 9 when it was tested? Would it help clear the algae faster if I increased the speed of my variable speed pump that is currently set at 2300 RPMs? Should I be backwashing daily, even if filter pressure hasn't gone up by 25%? Our pool is fiberglass so I normally see a lot of progress after the first 3 days and I've never had a SLAM that lasted more than 5-6 days. I'm not going to be around next weekend to add chlorine to the pool so I need to get this pool cleared up before then.

 

[kellyfair]

Round up CYA to the 10s, so you should be dosing your pool at the FC level for a CYA of 40. You can also test every two hours, if you don’t mind using up your reagents faster.

If there is debris on the bottom, it will definitely slow down your SLAM. Make sure you are brushing everywhere, and perhaps go ahead and vacuum to see how much crud you get. Vacuum to waste so you don’t gunk up your filter.

And above all, patience. It can take several days to completely clear a pool.

 

[al27]

Round up CYA to the 10s, so you should be dosing your pool at the FC level for a CYA of 40. You can also test every two hours, if you don’t mind using up your reagents faster.

If there is debris on the bottom, it will definitely slow down your SLAM. Make sure you are brushing everywhere, and perhaps go ahead and vacuum to see how much crud you get. Vacuum to waste so you don’t gunk up your filter.

And above all, patience. It can take several days to completely clear a pool.

I didn't want to vacuum to waste because it will lower the CYA. I took a sample to a pool store and was told that the CYA is 28 so I worry that my test results aren't accurate and CYA is actually 30 instead of 35 or 40. If there are some leaves down there, will it eventually clear up enough to see the bottom so I can get them out with a net? I honestly don't think there are many leaves down there because I don't feel any leaves when I brush the floor.

Would it help if I increased the speed of the pump higher than 2300? Or can I reduce it back down to 1500-1800 to save electricity since I'm running it 24/7? Would it help if I backwashed daily, even if the filter pressure hasn't gone up by 20-25%? Could I damage the gelcoat if I got the FC up higher than 12 ppms at night so I don't have to go out in the dark to test and add chlorine?

 

[kellyfair]

Following the SLAM exactly as written is the best way to clear your pool. I would not raise your FC any higher than SLAM level, for all the reasons mentioned by others here.

You really need to test your own CYA and don’t bother going to pool store to get it done. Test at same time of day, outside, with sun behind you. Pour your solution to first line, glance in (don’t stare) and if you see dot, pour to next line, glance in, and if you see dot go to next line. The line where you can’t see the dot (at a quick glance, not a stare) is your CYA.

 

[kellyfair]

And I agree with Marty about your RPM. You want the flow to allow the filter to catch debris, not to force it through. Also, you don’t want to backwash too often. Sand filters are actually a little more efficient when slightly dirty. Debris filling up the holes between grains allows even finer particles to be caught. But once the filter pressure is too high, then you are impeding any flow. That’s why you backwash at 25% higher than norm. Do be sure to rinse for a minute afterwards, to allow sand to resettle.

Oops! I quoted Marty in a thread that he hasn’t posted in yet! LOL