I’ve tried a couple of different closing kits over the years, and the one that’s worked best for me has been the Doheny’s kit. Nothing fancy about it, but it kept the water pretty clean over winter and I didn’t open to a green mess in spring. I still had to do the usual balancing when I reopened, but no algae bloom or heavy scrubbing, which was a relief.
One thing I learned the hard way: the kit helps, but it’s the prep that really makes the difference. I always shock the pool a day before closing, vacuum it thoroughly, clean the filter, and make sure the water level is right before putting the cover on. If any of those steps get rushed, even the best kit won’t save you from algae.
So yeah, a good kit matters, but the extra 30 minutes of prep is what really pays off when you open the pool again.