In my breeding and nursery tanks the pH runs a little higher than my others, about 7.4.

I think that the hardness is a little higher too.
I haven't tested it lately, but my tap water is high pH, and rather hard.  
This tank usually gets mostly conditioned tap water because it is upstairs, and I'm always forgetting to bring other water up.

My KH runs between 2 and 3 degrees, or 35.8-53.7ppm.

My GH runs between 8 to 10 degrees, or roughly 140-180ppm.

Another thing with the spirulina, two of my "female" swords that I got from Pisces Moon, have now turned out to be males!!
(She thinks I'm feeding them Viagra for fish)

Roughly same pH 7.2 and hardness 9 degrees.
Weird, huh?

The last litter that I had did produce many males, and the mother is still pregnant. I fear, however, that she has been withholding delivery and have never had a female holdout this long.

She's still a rather small guppy, and eats well,
and I've tried all the tricks that I know. I guess I'll just have to wait.

I'm sure once the swordtails are moved, she'll "pop" a bunch out, I just hope they'll be O.K.

Hope this helped, sorry I took off rambling on you.

Take care,