I was wondering what batteries you believe would work best for a solar run water purification unit. Are there ion batteries available? They must be sealed and ranging from 160 to 200 amp.
Sorry, but not enough information to make an informed guess.
Sealed could mean AGM batteries which are better for “float” service where batteries are kept at full charge and only occasionally need to be discharged. Sealed gel batteries are better for daily cycling and cold temperatures.
You did not indicate voltage and amp load of purifier, if the battery will be charged each day, and if it will be deeply discharged each night. Will it provide power for several days with no sun and deeply discharge, or is the load small in comparison to battery capacity?
Batteries are usually sized based on their voltage and amp-hour rating. Saying 160 to 200 amp would normally mean the load is this big, but most water purification units that use ultra-violet light are usually a small power load so I assume you actually mean 160 to 200 amp-hour. I also assume this is a 12 volt DC system but you did not say and this would change the number of batteries in series or parallel.
Not sure what you mean by ion batteries unless you are talking about the small lithium-ion batteries. These do not like to by cycled very deeply and will only last about 2 years.
Hope this helps,