water testing...... GH still not high enough?

after several days of 'putzing' around with water testing (only really
stared this because koizyme said it needs alkaline water) I still have a low
GH.

here is what I did: (3800 gallon pond) water temps . from thermometer, I
have no idea is working correctly said 65 degrees

also the1st ph reading was about 8pm thursday, then I took one at 6 am fri
morning, they were pretty close.(so I think the ph is stable, didn't look
like it crashes)
thurs: 1st reading
PH 7.5
ammonia 0
nitrite .3 - .5
nitrate 5-10
GH 40-60
KH 60


added 2 lbs of baking soda & 4 cups of dolomitic lime + salt

no change in readings except ph went to 8.0

added 4 more cups of dolomitic lime

ph 8.0
salt .11%
O2 10 mg/l
ammonia 0
gh 60
KH 90
nitrite . 0.3
nitrate ~ 8

the ONLY thing that changed , really was the KH went up.

I read that the lime will not dissolve in water with over 7.5 ph ,,
(correct??) I do see a lot of white laying around on bottom of pond.
sooooooooooo do I just leave this as is? I figure if the stuff isn't
dissolving , more won't help.
or is there something else to bring up the GH?

or should I bother?

( I read you can also use qypsum, but there is the danger of shooting the ph
off the scales........ or should I make one of those plaster of paris
cupcakes?)