Unstable PH

Just read the PH Rant thread... ignore this post, LOL

 

When are you testing your pH?
Are you testing at the same time each time?
These make a big difference in pH levels!
Dissolved carbon dioxide levels can also effect your pH.
Salinity levels and alkalinity can also play out on pH!

 

RO/DI water?
You really should get a Mag testing kit, or if you have one, see were it stands.
Your other params suggest it should be ok.
Water is a big deal...from the sound of it your most likly have a RO/DI...but then the next question would be TDS? Has this been checked?
Just a couple things... good luck.. ; )
LG

 

wow - loaded question.

What are you testing with and are you testing the same time of day?

your tank is always metabolising (converting sugars and Oxygen to carbon dioxide) carbon dioxide accumulates and lowers your PH (like glass covers on your tank prohibiting gas exchange)

day time permits photosynthasis which uses up the carbon dioxide faster than its created. but all in all this really shouldn't be more than a .2 or .3 swing.

(wow, you guys are FAST here ! I typed my response and then I see two already posted when I was typing....I love this site!)

 

Ph is probably unstable because of your ALK. Alk is unstable because of your high calcium and lack of MAG, which pushes alk down. Both alk and calcium probably got out of sync because of low MAG. So many steps need to be taken.

First raise alk to about 13.0 dkh (be careful and do it slowly and monitor ph)
Second get a test kit for Mag and make sure it is in the 1300-1400 range, add if needed. I would bet you are low.

Then monitor all 3 alk calcium and mag. Keep alk at 13.0 until calcium drops below 500, once below 500 you can start letting them fall together to whatever value is good for you with alk and calcium. Then you should get a steady consumption between calcium and alk.

Always maintain MAG levels also, it is a very important part of the balance between calcium and alkalinity. If CAL, ALK, and MAG are in the correct ratio it will be much easier to maintain. If they are out of balance it takes A LOT of work to bring the balance back sometimes.

 

Reefer and Crimson....Correct on the time of day.
Mine is a few points higher in the evening without fail.
I remember when I was having the same concern, Mission squared me away on the testing time difference.
LG

 

That is weird that you pH reading is lower at night. PH historically drops at night due to increased carbon dioxide in your water as photosynthesis stops, unless you run reverse daylight lighting over a refugium housing macroalgae!

 

You are absolutly correct...I got it backwards:-[ still on the coffee!

LG
but I gotta check my journal when I get home...brain dead here. I do run reverse daylight mico algae fuge..

 

OMG, in the 5 min this post was up before I changed it 7 replies! This is such a great site

PS. Mag test kit was out of tests, new test kit will be here in the AM... but last time I tested Mag is was in the optimal range.