water tests

[tanhql]

for most water test kits out there, most don't provide the colour card for brackish water, like the AP ones. so, if the SG is quite low (around 1.005), which colour card should the reading be taken against? the freshwater or saltwater card?

[Nusquam]

I think part of the instructions said something like if the salinity was low enough (light brackish) to use the freshwater, so that's what I'm doing (and plan to do until my s.g. is around 1.010). Although, my s.g.'s only about 1.001, so maybe someone else with more experience will pop in.

[Nick]

My SG in Shakespears tank is right around 1.012, raised gradually from the 1.002 he was in at the fish store. Since I have it split right down the middle, I check it closely on both cards and take an average.

[Norway Reef]

If your SG is 1.005 or less use the freshwater test kits, if it's 1.010 or higher use marine test kits.

[jake_vdb]

If your SG is 1.005 or less use the freshwater test kits, if it's 1.010 or higher use marine test kits.

This depends entirly on the kit. I have an API freshwater master test kit, and the only test that works with my 1.005 sg brackish water is Nitrite (which is specifically labeled as freshwater/saltwater). All other tests (pH, Ammonia, Nitrite) produce colors that don't even match up to the provided cards.
I replaced my API kit with individual Nutrafin kits that are for both salt/freshwater.