05 LaPalma body black tank question

[WeatherTodd]

Anyone know if the black tank design on the 05 lapalma series is supposed to have an inch of water that cant be drained??
I can see the black tank floor through the toilet and can see where the "high" point is on the tank when filling. But when dumped empty it seems there is still water retained in the tank. Im guessing its by design but just wanted to verify.
Tank level indicators do work and gate valve seems to work fine.

[Arch Hoagland]

I guess it would depend where the drain is located and if you are perfectly flat.

I have two black tanks in mine and can see the bottoms with no water after they are drained.

However after I drain the tanks I put maybe a gallon of soapy water in each tank. I don't want it dry. If there's any solids left I don't want them to dry and stick to the tank.

[WeatherTodd]

well I dumped with the drivers side slightly lower than the passenger side and it flows like gangbusters when draining and since the drains are on that side. No solids were left in the tank as I dumped 3 times and the last 2 times the drain line showed it clear.

I like to put about 5 gallons in the black tank just to dissolve the holding tank chemical.