Brightwell Aquatics NO3 Brick Crumbling Away

[mtnrunner]

I added a Brightwell Aquatics NO3 Brick on 1/5/2017 and as of today, 3/26/2017 I've found it is just crumbling away into find particles.

Any ideas why?

Alk 9.3
Ca 420
Mag 1250
Temp 77
SG 1.025
Nitrate 25

 

[lion king]

How's the flow rate, most no3 export products require a slower flow rate; maybe a high flow rate causes crumbling. Most report these brick type products crumbling over time, but 2 months is pretty quick.

 

[mtnrunner]

It is in a very low flow area of sump.

 

[wkscott]

Your numbers look fine, but what is your pH? A lower pH could possibly cause faster erosion. Just guessing though.