I just cleaned 4 powerheads with the stronger blue jug of Muratic acid. Here’s how it worked for me and what I found out.
At first I tried a 10:1 solution and it was working but a little weak for my taste. Still faster than vinegar though.
Then I tried a 10:2 solution. Faster but will still need a good 12 hrs or more to soak.
Then I moved to about a 10:4 or 60% acid to 40% RO (check my math. Not sure if that’s right). I think I measured 800ml of acid to 300ml of RO. I did this in a large clear container that I could see through. You could literally see those little white barnacles bubbling off. I did the powerheads for about 4-6 hours and that got them loose enough to where I could scrub them clean very easily with a brush.
After that I was having so much fun that I did a 10:5 or 50% acid 50% RO with my magnet cleaners and woo hoo...that was cooking a little too quick!

Couple hours and they were slick. Honestly that was a little too strong maybe. The plastic felt kinda greasy after that. I soaked then in vinegar for a bit and then bleach. It seemed to get that greasy feeling off and I was just a little hesitant to stick them back in my reef. Felt like they might leech plastic into the water. After they dried they felt a lot better and safer. Put my small one in first for a few days and no ill effects on the Acro’s so after a week I returned the larger ones.
My Jebao powerheads had some clear plastic seals and they were ok (no damage) in the 10:4 dip. I wouldn’t recommend anything stronger than that. In fact the 10:1 or 10:2 will be a fine choice and just go a bit longer if you have time.

I’d use something clear so you can monitor the effects.
I’ll say this...vinegar is too slow for me. Acid from now on!
FYI I did use a 3M painters mask with vapor filters and lab goggles and a pair of thick rubber gloves. These can all be purchased at Lowe’s and maybe Home Depot. Acid can harm your lungs and cause irreversible damage. It can also burn your eyes, skin, and hands. It is no joke and should be used with extreme caution.