Alkalinity Dosing Dropped

[cperry7467]

I've got a head scratcher I could use some help with determining possibilities. In summary, I went from dosing 100ml of Alk and Calcium a day to maintain down to 50ml in about a week and can't figure out why the tank isn't consuming it as quickly. Normally it's 1 of 3 things. My pH dropped because my CO2 media is out, or nitrates/phosphates are at 0. But that's not the case right now, pH is still high, nitrates 10ppm, phosphates 40ppb. What else could cause it? It makes me think my coral aren't happy and not using as much which obviously means something is wrong but I don't know what it could be!

A little more detail. I run a Trident along with Trident controlled dosing of BRS Pharma 2 part. My mag 2 part I just recently setup (a month ago) and haven't found the right dosage yet so my mag is a bit high at 1500. It was actually right about the time it passed 1500 that usage of Alk/cal dropped. I also have a kalk reactor to keep pH up, it's not enough to contribute significantly to my alkalinity though and it's been running for a few months without any changes. I also run a CO2 scrubber on my skimmer. When the media runs out I see my pH drop over a few days and know to replace it. If I get lazy and wait a week I've seen my alk/calc usage go down a little but not like this. Plus my pH is at 8.31 unless my probe is suddenly acting up so I don't think it's the media.

I'm planning to send in an ICP this week but any ideas in the meantime? My coral look happy and seem fine but concerned something bad is coming if I don't figure this out quick.

 

[Queen City Corals]

Have you manually tested yet? I have noticed that Tridents have a tendency to get messed up on occasion so that would be my first guess.

 

[cperry7467]

Have you manually tested yet? I have noticed that Tridents have a tendency to get messed up on occasion so that would be my first guess.

Yea, I actually had just changed my reagent last week on my Trident so at first I thought it was that, but I tested with my Hanna and it was pretty close. Trident was about 9.5 and Hanna was like 9.3.

 

[Queen City Corals]

Yea, I actually had just changed my reagent last week on my Trident so at first I thought it was that, but I tested with my Hanna and it was pretty close. Trident was about 9.5 and Hanna was like 9.3.

That is definitely weird like you said it could be your pH probe malfunctioning but that doesn't seem super likely especially if it's stayed consistent. I would definitely send out an ICP test it could be some sort of contaminants like a heavy metal or something causing a decrease in growth that hasn't materialized yet in the coloration of the coral.