Harlequin tuskfish Choerodon fasciatus; it is crucial to perform regular water changes in a frequency and amount appropriate to the bioload of your
system, which can be considerable with marine predators.
important. With marine systems (notice
how we increasingly say “systems” instead
of “tanks”—only with a marine audience is
such terminology appreciated!), pH goes
hand-in-hand with hardness, alkalinity, etc.
In general, the sea salt mixture you purchase
to make up new salt water buffers and
adjusts the major elements (magnesium,
calcium, etc.) and the alkalinity for you.
So, everything works out nicely if you
just perform water changes on some type
of regular schedule—a load of potential
problems will be taken off your shoulders.
Frogfish Antennarius maculatus; it is normal for an aquarium housing predatory fish to have high
levels of nitrates, so testing for nitrites and ammonia is a better method for detecting a decline
in water quality.
One very important area that sea salt
mixtures cannot adjust for is the beneficial
bacteria that are the backbone of most
aquarium systems, both fresh and salt. If
the chemistry of the water in your tank is
allowed to change significantly from that
of your freshly mixed replacement water
because of accumulated pollutants, it is
possible that very large water changes will
actually shock the bacteria and kill them off,
thus causing the basic nitrogen compounds
(i.e., ammonia, nitrite, and nitrate) to build
up to toxic levels. So even though I still
preach that the more water changes, the
better, it’s important to understand that you
may need to ease into them if your current
regimen is less dedicated.
To wrap up water changes, here’s what
I think works well for most people who
have an aquarium that is already cycled and
established: test your water for ammonia
and nitrite once or twice a week. If the
results of either of them are outside the
acceptable levels according to your test kit,
then do a 30-percent water change. Test
again after 24 hours. If any compound is
still too high, then make sure to perform
another water change as soon as possible.
Notice I left out testing for nitrates.
Tropical Fish Hobbyist