George Patterson wrote:
drain my
tank down to a specific point on the glass (ie. 25 gallons low),

Yep, it's less efficient, but it does enable the mark on the tank
technique which seems to be more or less standard based on every book
I've read.

I opted against this for two reasons:

1- less efficient at removing waste as you're diluting your tank before
draining a percentage.

2- what if you over drain by accident? If you have enough extra salt
water, you're in luck; otherwise, you're mixing up more salt water.

3- you're limited to draining only xx%. What if you want to do lower
cleaning and/or more siphon cleaning?

I'd rather keep it a bucket and use it for make up (if needed) after the
silt settles a bit. If you do that, there's no advantage to the mark on
the tank technique and a few disadvantages.

I guess it's less of a big deal now as I keep my evaporative makeup at
less then a gallon.

--Kurt