I ended up having to run to Lowes yesterday afternoon so I picked up the rock cleaning stuff. Two pack of Kem-tek muriatic acid, 3 boxes of baking soda and some long nitrile gloves. The acid was in the pool section and $11.99 for two pack of "contractor" strength 31.45%. It only took a couple hours last night.
I used an old sterilite 45g container, an old Mag 7 and of course safety glasses and a garden hose outdoors in an open area staying up wind of the tub. I really just wanted a light etching on the rock and didn't want to over do it like I've seen in a lot of posts. There was some old algae left on some of the rock and probably should have bleached it but it hosed right off after the acid. That rock has been in storage at least 8 years and the hair algae that remained was still green and even looked alive after rehydration and acid!!
It took two container runs to get all the rock done and I just used 1 gallon of acid and about 1.5 boxes of baking soda per. I really think some over do it on the baking soda and that's why they end up with hard encrusted soda on the rock. As far as the acid goes there was no mm's of rock removed or other destruction some have experienced with certain types of rock and/or excess use of acid.
1) Tub with rock and pump filled with water
2) Acid added
3) I did occasionally knock the foam head off with light water spray to help carry away the worst of the grunge that the foam traps.
4) No real timing but just waited until the reaction stopped at < 1 hour.
5) Lightly sprinkle on about 1/2 a box of baking soda at a time and wait for reaction to stop. By the 3rd .5 box the reaction done.
6) Attached hose to Mag 7 and drained.
7) Refilled with fresh water and allowed to circulate a while with fresh water running in/overflowing.
8) Rocks removed and hosed down to remove any leftover green stuff. That and any grunge hoses right off.
I also picked up some new 20a GFCI outlets but feeling kinda lazy today. Maybe sometime this weekend...