high gh using distilled water
Hi. So I recently checked my water parameters on my heavily planted low tech 20g and was surprised with the high gH. I used the gh tester from api and saw the gH was 16 (16 drops for water to change to green). I was confused by this because I use only distilled water. I do not do wc and just top off when it gets low. Does anyone know the reason for this high gh? My water has 0 ammonia, 0 nitrites, and 0-5 nitrates.