de "Watering" holding tank

[capav8r]

Does anyone have a good way to completely empty the holding tank? 2006 2600SE. Last year I got most of it out (all the pump out could get) then ran a gallon or 2 of RV anti freeze into the tank. Apparently, the "solution" that remained still froze, causing the clamp to slightly expand and loosen up enough to leak the remaining liquid into the bilge. Nice surprise come springtime. If you know of a way to empty it, please let me know. Otherwise I guess I will just add more anti freeze this year.

[dronthelake]

A couple weeks ago sanitized our tank with a little bleach. Ran the water/bleach through all the faucets then refilled and emptied the tank twice. After the 2nd empty I removed the water level sending unit and slide a 1 1/4" shop vac hose into the tank to get the last couple gallons. I removed the water level sending unit from the top of the tank. I worked it around until there was only a cup or two in the bottom. Then I added about 20 gallons two more times to get everything out.

[seapuppy]

well...let me ask you this...did you add the RV-AF to the head and pump it thru??..cuz if you just poured it into the top of the tank..then no wonder the bands expanded.....

go to a local pump out....pump the san tank out...add some water and pump out again...do this a few times...the go into the head with 2 gals of rv-af....pour it into the toilet bowl and pump thru....leave about a pint in the bowl...your done.....shouldn't have any problems after that..


SP

[capav8r]

Hey SP. The procedure you outlined is exactly what I did last year. In looking at the tank this year, it looks like there is probably 1~2 gallons of water left that the pump out can't get. I am guessing that much water dilutes the anti freeze too much for our winters. I believe we saw -27 F last winter. I am trying to figure out a way to get that last bit out somehow...before I run the anti freeze through the head.

[seapuppy]

then I'd add a couple more gals of RV-AF......

SP

[shrew]

I think SP may have nailed. It is my understanding that the -50F for the pink propylene glycol is based on being undiluted. 2Gallons of AF with 2 Gal. of fresh water will significantly lower the value. The mixture in the tank is now only -25 or even higher. I've been told (I've never seen it) that the pink AF can get slushy. I'm not sure if hte -50F is the freezing point where it becomes a true solid or where is starts to slush up. I'd guess that it is the freezing point where it becomes a true solid. So if the diluted value is below the temps in the area, then a mixture with a value of -25F would certainly freeze in -27F temps (IF my assumption is correct).

I wouldn't go with a -100 as it is my understanding there are additional chemicals and anti-corrosives added. I'm not sure how that would do in a plastic holding tank. I know only the pink stuff is recommended for freshwater tanks.

[capav8r]

Shrew, you are right. The pink stuff turns slushy around 0 F. The -50 rating is where it turns solid, expands and breaks stuff. You are also correct in that diluted RV antifreeze freezes solid at a much warmer temperature. I am thinking that it is probably more dramatic than what you would guess. That is why I am looking for a clean way to get as much water out as I can prior to adding the AF. I was thinking of a pump of some sort with a 1/2" or so hose that I can slide down the discharge line. Problem is-I don't have such a pump in my garage collection and am not sure where to get one. I am also considering loosening the clamp at the discharge connection to the tank and just let it expand. At least it wouldn't stretch the clamp any further. I will just have to make sure tightening it back up is on my commissioning checklist. I don't think anything else in the tank can really get hurt by freezing solid.

[seapuppy]

look ...your over thinking this ...if you really want to get all the water out...use a shopvac to get it out...they do a good job of evacuating a tank....
if not..then just add about 4 gals of RV-AF and let it ride..I will bet dollars to donutes it will be fine..


SP

[shrew]

mmmmmm donuts. ditto. keep pouring. I would have no problems tossing the entire case in there if I thought it would let me sleep at night all winter.