How much PH Drop from Calc Reactor alone?

[Dominican]

I recently set up the Milwaukee PH controller I got with a CO2 kit from Aquacave, just to start reading PH real-time until I get the reactor. After determining that the probe is working ok after having arrived dry (I did some rinsing with the calibration solutions, it's responding quickly, and it read pretty concisely to the 4&7 during calibration) I found that my tank PH runs high - 8.4 during the day and 8.5 at night. Tap water here read at 10.1 (is that normal?!?), and my reservoir, after running through a Spectrapure 3 stage RO, is 10.5. That freaked me out too - any comments? Alk is at 11dKh. Calc at 400.

So I'm telling myself I'm close to figuring out what kind of Calc reactor I need (sorry for the delay Ace, if you're reading this). When I get one set up though, how much of a PH drop should I expect?? Being that my PH runs so high, would it possibly mean I could forego a kalkwasser reactor, once the Calc reactor is up?

I defer to your expert opinions, thanks...

[Richard]

I think you need to verify that the probe/monitor is reading correctly because those numbers don't sound right. Your ph should go down at night, not up. And tapwater at 10.1 doesn't sound at all right.

What is your alkalinity? Since ph is directly related to alk, you can tell if the probe is at least in the ballpark if you know the alk.

[JimD]

"What is your alkalinity? Since ph is directly related to alk, you can tell if the probe is at least in the ballpark if you know the alk."

"Alk is at 11dKh. Calc at 400."

[rz1a]

isnt pH of pure water supposed to be at 7 on the pH scale?

[Jamie]

pH of 7 is neutral...meaning not acidic nor alkaline. I think that absolutely pure water...ie RO/DI with 0 TDS...should read zero for pH.

[hobogato]

RODI of zero TDS should read pH of 7.0

our tap water here in SA has a TDS around 350 and a pH of about 8.5

[Richard]

"What is your alkalinity? Since ph is directly related to alk, you can tell if the probe is at least in the ballpark if you know the alk."

"Alk is at 11dKh. Calc at 400."

Oops, missed that sentence. Well, your tank should be around 8.4 at 11 dKH.

Edit: Reefkeeping won't me link to the chart. You can find it in this article...
http://www.reefkeeping.com/issues/2005-03/rhf/index.php

Pretty weird to have tapwater that high. The EPA max standard is 8.5. I've notice my RO water is about the same ph as the tap at first. When it's aerated the ph drops down.

[Dominican]

Ok, so at least the tank PH matches the Alkalinity. I'll retest the tap and the reservoir again in a few mins.. The reservoir is in the garage where it gets pretty hot. It's in a big rubbermaid trashcan, about 70 gallons.. Not sure if that makes any difference. Either way...

So, tentatively re-establishing that PH=8.4 and Alk=11dKh, how much could I expect ph to go down with a Calc Reactor & CO2 running?

Oh, and you're right Richard. Sorry I had the day and night backwards...

[hobogato]

if my kalk reactor needs kalk added, my tank pH runs 7.9 to 8.1 with the calcium reactor. once i add new kalk to the kalk reactor, the pH bumps back up to 8.2 to 8.4.

[Jamie]

Sorry about the bad gauge earlier...I got some information streams crossed. Pure Ro/DI is indeed 7.0

[Dominican]

Ok so avg of maybe .3 PH drop.. hmmm.. That would put it between 8.1-8.2. Thanks Ace.