Need help with water chemistry

[selch]

To get to the point, I'm having issues with my Ph, calcium levels and ability to grow coraline.

 

I'm running a 50g tank with a 10 gallon sump, use an RO/DI filter for my water and a dosing pump with B-ionic. I'm dosing B-ionic in equal parts and I have good water movement across the top of the water surface. Also, running a 150w MH with 2 65w actinics.

 

My Alk measures right in the middle of the prefered range. (I can't remember the exact number off the top of my head - but it is fine. I'll get you the number if you need it.) My Ph always comes in at about 8.0 and my calcium is a staggering 650.

 

I know that I can temporarily reduce my dosing time on calcium to get that down but I've never been able to get my Ph to around 8.3. I think this is the reason why I have a really hard time growing coraline and keeping it.

 

This is my second tank, after starting with a 12g a year and a half ago. So I'd call it mature as I just moved all my stuff over and added more rock. This move was about 6 months ago. I thought that b-ionic would even things out over time but its been about 3 months and things are about the same.

 

I'm wondering if I need another additive to get my Ph up and then back off and have the b-ionic maintain that level. Anyone have any thoughts on that? I've also heard that RO/DI water is more difficult to keep a buffer than regular RO. Even if so, I'm not hot on the idea of scrapping my water filter.

 

To recap, I need to get my Ph up a bit and get some coraline growing.

 

Thanks for the help.

[supernip]

getting your calcium down will be a huge help in getting both your pH up, and alk up.

 

I suggest water changes, and addition of baking soda for the time being.

Also, without more exact numbers, it's really hard to troubleshoot. alk, mg, no2, no3, po4 would be nice. As well, the brand of kit.

 

It would also help if you were able to list some of the inhabitants of your tank. I