Liner-
If you are going to have a deck you may want to get a beaded liner that doesn’t require you taking the top rails off to change out the liner later.
Filters-
I have a 250# sand filter on my 25k gal pool & it does a fine job. I have no issues with disposal/drainage of backwash water on my property. If you do you may want to consider a cartridge filter as you don’t backwash those like a sand or de filter.
De filters take up little space.
Each type has its pros & cons but
With all filter types - the bigger the better! The bigger the filter the less you need to clean it.
Sand filters are generally the cheapest so if that’s the way you can afford a decent sized filter then go for it.
Pumps-
If I had a choice I’d go with a 2 speed or variable speed pump. 2 speeds are more pocketbook friendly than vsp’s they just aren’t as customizable but low speed on a 2 speed is plenty sufficient for daily filtering/operation of a simple above ground pool.
Swcg’s-
Your pool will hold approximately 13,500 gallons. We do recommend a swcg that is rated for 2x’s your pool volume. So 27k gal rated or higher.
As
@phonedave mentioned in your locale with your shorter pool season & less harsh weather you may be able to get by with something smaller like a 25k gal rated system. Something with an output of 1#/day. Or possibly less.
* Here’s the deal - The larger the cell the less you have to run it & the longer it will take to use up its finite 8-10k hour lifespan in people years. The manufacturer’s gallon ratings are based on running the system at 100% 24/7 .
if you do this your cell will potentially get depleted in a few seasons and you’ll be shopping for a replacement cell sooner rather than later. Going larger is generally worthwhile monetarily for what you get fc wise.
Here’s a good comparison chart of popular systems so you can compare outputs, warranties etc. as they are not apples to apples (example: all 25k rated systems don’t necessarily have the same #/day output)
www.discountsaltpool.com
Example: I have a slightly undersized swcg now which leaves me needing to run my single speed pump for up to 12 hours in the peak of summer to properly chlorinate my pool - this adds up on the electric bill!
Being able to run at a lower speed would certainly lessen this burden as would a larger swcg.
The cheapest option for lowering the daily costs of operation & overall costs would be to employ both a larger swcg & a 2 speed or vsp although both options cost more on the front end.
www.troublefreepool.com