Water quality questions

[ramba]

I have a 55gal. , 25lbs. LR, that has been set up for 1 year. 1 yellow tail damsel, 1 false perc, brittle star, banded coral shrimp, 1 snail,1 hermit. CC and dolomite, wet/dry filter w/bioballs:both recommended by LFS guy who has masters degree in marine biology!?
With Tetratest kit: amm=0, trites=0, trates approx. 15 (somewhere btw. 12.5 and 25 are the choices), ph=7.8 or 7.9,KH=6. The ph of my freshly mixed saltwater is 8 and KH=11. Nitrates of tapwater are more than 0 definately, but less than12.5. When I tested for nitrates in the tapwater 3 mos. ago, they were 0.
I change 10% of water every 10 days.
When I get anRo/DI unit, will it help the ph? Should I use the Seachem reef advantage Ca the LFS recommended after testing my ph? Why is the KH lower in the tank than in freshly mixed saltwater?
Thanks!

 

[matti070]

no, RO doesnt change the PH. neither DI. the only difference RO/DI give from tap is it has less bacteria. im 75% sure.

 

[ramba]

Oh, I should have mentioned that I have well water. It is a 110 foot well...not sure where nitrates or bacteria would come from. Should have paid more attention in chemistry class. Thanks matti!

 

[slick]

Let me first say that RO/DI water removes 99.?% of junk in the water. Tap water has a lot of dissolved crap in it that you don't see.
Now I suggest you do a search on PH, Calcium, and Carbonite Hardness. Look for posts by Broomer5 he really knows his stuff.
I can't really give much more help on this subject.