Alkalinity testing

Texas Reefer · Aug 2, 2014

I'm a bit clueless when it comes to Alk. Working during the day, I am not home after the lights come on, so I always end up testing the Alk in the evening after the lights go out. My readings are generally below 7, so I dose. Well, today I tested at 2 in the afternoon, and the Alk was 9.6! I have a light in the sump on a reverse schedule, so I thought that would lessen any pH swing, which would help keep Alk stable. Am I completely wrong? I did, just last night, use a different brand of buffer. I generally use the liquid Kent Marine PRO buffer dkh , 5 teaspoons for my 90g DT/30g sump (actual tank dims). Last night I ran out of the liquid, so used Kent Marine Superbuffer-dKH. Instructions are to dissolve 1 teaspoon per 20-30 gallons of tank capacity. I mixed 5 teaspoons into a cup of tank water and added it to the return section of my sump. Did I do something wrong? Does alkalinity fluctuate so much during the day? What relatively inexpensive piece of equipment would measure the Alk and keep a record? I can't afford a fancy controller. Thanks for the help! And sorry so long!

mike007 · Aug 2, 2014

Get a Hanna alkalinity tester, they are very accurate. You do not want large swings in alk. it will cause you some problems. Alk should stay stable only ph will change from night to day. You need to test alk. and get it where you want it and go 3 days without dosing and retest. This will tell you how much your tank is consuming and then you can go to the brs reef calculator and determine how much you need to dose each day to maintain.

Kworker · Aug 2, 2014

+1 on hanna, its an easy kit to use IMO.

Texas Reefer · Aug 3, 2014

But what time of day is the most accurate?

Opus · Aug 3, 2014

It doesn't matter when you test for alk, you will get an accurate reading. It is a good idea to do it around the same time just because of the coral using up the alk. For example, testing in the morning would be higher than if you did it that night because some would have been used up by the corals during the day, assuming you don't dose during that time. I think the higher alk in your case is from using the kent superbuffer. I only use 2 teaspons in my 75gal tank to raise it up by 1 and you used 2 1/2 that much so I could see it going up over 2 points for you. As Mike stated, test it a few days without adding any buffer and see what the tank is using. Then that will give you a better idea of how much to dose.

Eckolancer · Aug 3, 2014

If you are dosing a lot at night you might have an up swing that slowly decreases over the day. How much alk are you adding and what is you cal and mag at? They all need to be in balance. I have my alk on a doser that doses every 90mins. I had it dosing every 4 hours but decided I wanted more of a gradually dose.

Ph will go up and down depending on the amount of light and co2 in the room. Here is a pic of my ph from apex. I don't really care where the ph is at. I just use it as a marker if I see a major drop or raise in a couple hour time I know something is wrong, as well as a gradual increase without a decrease.