Make sure you're FC is as close to SLAM levels as possible, keep brushing, make sure you brush around fixtures, and inside and around your light niche... There's definitely something left in your water. But not much.
Indeed. I found 2 little algae spots hiding either side of the rear of my skimmer weir where the hinge screwed into the box. Had to take the weir out to get to it and a toothbrush to get in and scrub them away. Without scrubbing that algae was just laughing at elevated FC levels. Next time I have a problem I know where to look.
That's a lot of chlorine!! Maybe you had an ammonia problem to start with...
Day 5 is kinda minimum if your SLAM is curative, expect another 2-5 days to finish it, but you should not need another 50l. If you do, then you may have a bigger problem... My last SLAM took 10 days (after I let my FC drop to 0 over a long weekend away), I used about 15-20l and my pool is slightly bigger than yours.
I do a preventative SLAM at the beginning, end and mid season and if there was no issue it's over in 48h
So the pool is looking great and I'm going to persist with it until I pass OCLT. Being the novice I am I need to post about these black marks, originally I thought they were stains of some sort....but I'm now considering that they could be algae? If I scrub nothing happens...any advice?
What can I test accurately with FC over 10? Everything except PH? Is there anything except chlorine I should be checking during a SLAM? I want to swim in a few days....even if I don't pass an OCLT in time, what would I do to make pool swimmable? Water crystal clear, CC 0.5ppm but still losing 2.5ppm over night
Mine was about $85 back in 2011. There's a hydroponics place in Malaga that has a reasonably good unit EZDO-6011. That's the little brother version of the one I have. I had a chat to the guys there earlier in the week about ordering a replacement electrode for mine.
The "problem" with a pH meter is you need to keep it calibrated. That's not an issue for me, but you'd need to keep some standard 4.0 & 7.0 solution around for periodic calibration and you really want to wash the probe with DI water and then store it in storage solution after use. I keep a squirt bottle of DI with my pool gear and have a 250ml bottle of storage solution I use to put some in the cap before I put it away.
The advantage is it works regardless of FC levels (or pretty much anything else for that matter). I find the advantages outweigh the hassle, but I originally bought it for other uses so I was already up to speed on calibration and storage. If you want it to last you must store it correctly. Let it dry out, store it in plain water or otherwise mistreat it and it'll last months at best. Mine is pushing 8 years now, so I'm not complaining about the investment.
I also have one of those cheap and nasties that I got for free when I purchased a cheap and nasty TDS meter :
It's awful and worth exactly what I paid for it, even when properly calibrated it's garbage.