Test strips are usless for pH, TA, CH, and CYA. They are about as useful as an OTO test for Chlorine, IMHO. However, there are a few specialty tests where the strips are either precise enough or better. These are salt titrators (less chance of operator error than the 'fussy' salt titration!), borate test strips (here the LaMotte win hands down over the AquaChek! The only drop based borate test still available is from Apollo Pools in Canada and it is an add on for the Taylor K-2006) and Nitrate, Nitrite, and Ammonia (not needed very often but useful in a pool that has a HUGE chlorine demand or persistent algae that just won't go away.) Bad news is that if the problem is nitrate/nitrite all you can really do is replace the water. Ammonia can be dealt with by LARGE amounts of chlorine