The easiest way to avoid algae problems is to not get them in the first place. I think you need to work on getting a phosphate remover you're happy with, and try and work out what happened with the PhosBan. I use Rowaphos now and am very happy with it, I have used Al based phos removers in the past, and have not been happy with them as they are less effective, and also can have bad effects on softies.
The shaving brush plants, halimeda, are not too effective at removing organics and outcompeting microalgae and hair algae. Yourtank is too small to even think about growing some caulerpa or whatever intank. I tihnk you need to consider, RO water, a P remover, and purchasing a decent skimmer like the smaller remora. Most of the nanoskimmers are junk, a factor of physics, scale, and shabby design, construction. Sadly making a skimmer smaller does not make it much cheaper. You need some kind of clean up crew too.
I have never tested for strontium, and iodine is tough to test for as it changes so quickly. For phosphate get a Merck or Deltec test, the others are pretty poor. I also gave up trying to interpret Redox in saltwater aquaria - the only people I know using them are people injecting ozone. There are two many variables.