It was time to head to the boatyard and annual service on the head systems. There weren't many trips this summer and August was spent rebuilding the steering system. The holding tank hadn't been pumped since July. So I pump the tank and refilled it with freshwater followed by another pumpout. Did this a couple more times till the pumpout water was clear.
Hears what the tank looked like:
The plan was to reduce the amount of SP and Tide and hopefully still clean the tank. I decided to mix the same batch ratios but eventually top the tank with fresh water. Mixed 2 batches and ran one into each head. Waited 2 days. Mixed 2 more batches and ran them into each head and waited 2 more days. Then kept flushing buckets of warm water into each head until the tank was full. Waited 5 days and pumped out the holding tank several times with freshwater refills in between.
Here are the results:
The ratio of cleaning concoction in the tank went down to between 20 and 25%. Was mostly happy with the results. More time may have been better, a higher percentage may have done more. Going for a beam roll in seas before pumping out might also help.
How this effected the Vacuflush:
It's been 5 years since I replaced the vacuum pump accordion plungers. I decided my maintenance schedule would be to replace them every 5 years and the duck bill valves annually. I decided last year to change one pump's valves and let the other ride another year to see if there was any noticeable increase in deterioration from the SP and Tide.
The cleaning solution works perfectly in prepping for the rebuild. No residue or smell anywhere in the system. The valves were indistinguishable from each other and almost like new. Imo, the SP and Tide seem to have no effect on them based on the exposure time. The plunger and orings were also unaffected.
Had some amount of Struvite in parts of the pump from some water conservation while in Lake Superior in 2017. Soaking the plastic parts in white vinegar overnight desolved all but the bottom of the pump housing. 20 minutes of muriatic acid cleaned the housing nicely. Both pumps rebuilt nicely and other than valve changes, should be good for another 5 years.