I recently got a cascade 1000 cansiter filter, and i was wondering how often i should change the filter medium, or what signs i should look for to see if it should be changed.

also how much salt do you add to a gallon to get optimal gravity?

thank you

You should change or rinse the media in the filter at least weekly.

To determine specific gravity I suggest you get a high quality refractometer - float and swing arm hydrometers are notoriously inaccurate. Specific gravity is not something that can be ball parked - you need to test it.

so should i rinse it with aquarium water, RO water or will tap water be fine

Rinsing the filters seems to be one of those areas where there are many different opinions. I am a purist who likes to use saltwater, but I've met other very good reef keepers who swear by tap water, even though it's supposed to kill bacteria.

Thales has given you good advice about the refractometer - I've never regretted getting the best.

Nancy

Just remember to calibrate the refractometer!!!! We had a student try to tell us the local seawater was 55 parts per thousand :shock: it was actually 35 which is normal, but the refractometer needed calibrated!

J