Recently I've found a post on a different forum with a recall on Hanna Alk reagents which happen to be spoiled.
If you haven't been checking your reagent before using them to make sure it's good, then do it now. So far five of my Alk reagent bottles were bad.
LOT 5423 IS BAD
LOT 5554 IS BAD
Go to this
link and enter your Lot number and see if you qualify for a replacement. From my research stores are still selling bad stock, so check before you buy!!!
I broke out my new and unused Red Sea Alk test and found the following:
My display tank running zeovit and been testing Alk with the same bad reagent batches for at least six+ months:
Yesterday I was reading 8.58 on Hanna and 10.2 on Red Sea(new kit opened yesterday)
Today I was reading 7.56 on Hanna and 9.1 on Red Sea - stopped dosing yesterday to lower dKh
Based on the bad Hanna reagent I've been running this tank at 8-8.5 on Hanna Alk Checker which in reality is 9.8-10.5. no wonder sps kept on slowly dying.
My frag tank last night was reading 9.52 on Red Sea and 7.62 by Hanna Checker, so a discrepancy of 1.9 dKh - not too bad on this as this system is not running on zeovit so it doesn't need ULNS (only problem is I just finished cycling this tank a week ago so its empty)