Go ahead and post a link: I'd like to know what it is they are calling a "baleen filter".

Regarding dilution: I haven't checked what Taylor says, but here are the facts:
1. You MUST used distilled water when using dilution to extend the range on a chlorine test, because you have to dilute with some thing that (a) is chlorine free and (b) is chlorine DEMAND free. That rules out tap water (has chlorine) and bottled waters (may have chlorine demand), leaving distilled water as the option.

2. You MAY use tap water when using dilution with a CYA test, since tap water is always CYA free, except in very rare circumstances.

3. You MUST use distilled water when using dilution to perform a phenol red pH test on water with high chlorine; distilled water is the only readily available water that is free of all pH buffers.

Regarding Xtra blue -- it's a diluted dichlor with added copper. If you haven't had stains yet, you may be OK.