cant hold my pH!! Xenia dying.

[psumba]

Need help desperately. I have been fighting this problem for awhile but this weekend just topped off my frustration:
My aquarium can not hold pH up at 8.2 it occasionally dips to 8.0 which just kills my Xenia.
Saturday morning all was good, the Xenia was happy. I added about 2 gals of fresh water to top off... next thing I know my Xenia is dying.
I checked the water 8.0
I ran checks for my alkalinity 6.0 meq/L
phosphate 0.4
Nitrate 10 mg/l
ammonia = 0
I have checked fresh tap water before and it read a pH of 8.6 so I dont think that is the problem. What is the chances that the tap water varies drastically?
I use Kent Marine Superbuffer dkH every 2 weeks.
It looks like it works great for alk but its not locking my pH very well. Anyone have any ideas, or another product(s) to try?

 

[iechy]

I had a pH of about 8.0 as well when using tap water. When I switched to RO/DI water the problem was fixed. As far as I can tell this is only one of MANY reasons to use RO/DI water. It is well worth the money. I buy it for $1.00 for 5 gallons. Considering how much I spend on everything else in my life (diapers) it is just a drop in the bucket (pun intended)

 

[psumba]

Ro/DI water huh?
This helps you lock in at 8.2?
$1 per 5 gallons? Where do you buy it?
Any reason that you know of why this happens to tap water and not RO/DI?

 

[iechy]

It could be a coincidence though I think I've seen others mention it before. Maybe one of the Sharks can give the reason. With all the additives and crap that are added to water to keep it from making you sick there are lots of other things going on in it. Also I would assume that tap water is very different where you are and where I am but regardless it is better for your tank anyway. I but mine from one of those little kiosk type things in the parking lot of the grocery. I bring my containers and fill them up for a few bucks. One thing it definately helped with was diatoms. They were all over and now they are gone. Worth my money for sure. HTH

 

[saltyrich]

Actually, I believe that RO/DI water should be neutral. I'm certain one of the sharks will expand on this. You'll need to add a buffer to your RO/DI water (strongly recommended), to bring it up to 8.1-8.3. This is where most reefers like it. What are your alk levels? There appears to be a relationship between ph, alk, and calcium. I'd use a good buffer like seachem or Kent's to get the ph to where you want it. In addition, I'd attempt to get your calcium and alk levels to 420-450 and 3.0-3.5 respectively. Then, maintain these levels. Many experienced reefers drip kalkwasser. I'm not quite there yet, so I use a two part supplement to maintain ph, alk, and calcium. I've used C-Balance as well as Kent's Tech CB.