Chemicals to clean the sand filter?

I have an AG pool and a sand filter. Got it last May and have only used BBB. I did notice on a paper from the store where I bought the pool that they say the filter should be cleaned with some sort of chemical twice per year - once before closing and again around July. Do any of you go through any sort of filter cleaning process or is that only necessary if you use other products to maintain the pool? I have heard that Baquacil will gunk up the sand in the filter over time and this particular store really pushes Baquacil.

No need for it, unless you own a pool store and want to make more money.

If you use BBB and backwash your filter you will NEVER need to do this. I'm now on my 5th season without ever doing anything of the sort. This is just one of many useless pool store scams

Here's a few of the Barnyard Slush (BS) items:
1) Chemical treaments to "clean" your sand filter
2) Bacquicil and all its side products
3) Bleach adds lots of undesireable total dissolved Solids (TDS)
4) Liquid Chlorine isn't the same as bleach.
5) TDS
6) Phosphates
7) Phosphate removers
8) Nature2
9) Lower T/A by creating a bolus of muriatic acid.
10) Total Alkalinity Raiser is somehow different than baking soda and justfies prices 4 to 10 times higher.
11) You need calcium in a vinyl pool
12) Your T/A can't go over 120 in a vinyl pool.
13) Chlorine levels higher than 3 are dangerous.
14) Chlorine smells bad and it's the chlorine that give your pool that disinfectent odor.
15) Chlorine irritates your eyes and skin.
16) You can't safely test your water yourself
17) You need LOTS and LOTS of Chemicals RIGHT NOW!

Anybody got any to add?