Seachem Alert Series Alert ComboThe Seachem Alert Combo pack is a revolutionary way to keep tabs on your aquariums essential levels. This unique tester provides continuous pH and ammonia readings for up to 6 months, eliminating the need for strips and complicated tests. Continuous freshwater pH and ammonia readings No strips, no tests, just constant readings Up to 6 months of constant monitoring Alert Combo is easy to use: just place each reader somewhere visible in your aquarium,