Alk jumped from 7.7 to 9.9 during cycle

[stylolvr]

After 4 days of consistent alk levels with a Salifert test during the beginning stages of a cycle, today it reads 9.9. I figured I messed the test up so repeated with the same result. It seems like too large of a jump to not be user error.

I finally started my Waterbox 20 Cube this past Saturday using WWC mixed water and have been testing alk, ammonia, and nitrate daily (pH tests arriving tomorrow - shipping delay...). Ammonia and Nitrate are acting appropriately (see below) with ghost feeding.

The water has the classic white milky cloudiness, and I know that the 0.5 and below readings are basically useless, but the test has also gotten a bit cloudier in the past day or so. Any ideas? Thanks in advance for the help!

 

[Randy Holmes-Farley]

Unless you did a water change, or nitrate declined substantially (which perhaps it did), it is likely test error. Just because the current value is reproducible with a given kit, doesn't mean that it or the earlier value(or both) are necessarily correct.

Top of is RO/DI, or tap water (the latter can contain alk)?

 

[stylolvr]

Thank you. I feel like it has to be test error. I haven’t done a water change yet and nitrates have slowly started to increase with a few days of ghost feeding.

Top of is RODI also from WWC with an ATO.

 

[stylolvr]

Tests this morning reflect similar results to yesterday.

Temp: 77.4
Alk: 10.2
Ammonia: 0.25 (or at least less cloudy than yesterday - still essentially a nil value)
Nitrate: 10 (a good sign!)

I think I was just conducting the alk tests improperly the first few days. An alk of 10.2 doesn't seem unreasonable, it's more about consistency, right?

 

[Reef.]

What alk is the salt?

 

[stylolvr]

I'm using pre-mixed Brightwell NeoMarine from WWC. I didn't test the alk of the water before I added it to the tank, but their website says it mixes to about 7.5. So perhaps the 10ish results are wrong? I'm headed into WWC today anyway to pick up a glass cleaner so I'll take a sample with me to see what they come up with.

 

[stylolvr]

WWC tested alk at 8.3 so I guess I need some practice with the test procedure. They confirmed my other parameters and agreed that the cycle is almost complete. Just a waiting game now. Thanks everyone for the help!