Hot Tips: Common Mistakes Setting Up A New Tank

A selection of useful tidbits of
information and tricks for the marine aquarist submitted by
Advanced Aquarist’s readership. Readers are encouraged to
post them to our Hot Tips sticky in the
Reefkeeping Discussion
forum or send their tips to
for possible publication. Next
month’s Hot Tip theme will be
Circulation System

Common Mistakes Setting Up A New Tank:

  • Mistake number one: Not installing a GFCI before setting up
    the tank and stand.

— Laura D

  • heavily stocking a tank within the first few weeks of the
    initial setup
  • not providing adequate water flow around, under, and
    through a rock structure (dead spots)
  • placing damsels in a tank (intended to be a
    “community” tank) to “cycle” the tank
  • listening to 10 different people’s opinions all at once
    (find one person who has a tank that you like and follow their
    advice until you get on your feet)
  • impatience
  • not using RO water

— melas

  • Using an external overflow.
  • Underestimating the flow required.
  • Stocking too fast.
  • Overfeeding.
  • Overestimating how many fish can fit in a given space.
  • Putting fish that get large in small tanks because a larger
    tank will be purchased “a few years down the
  • Placing parts and equipment that need to be frequently
    maintained (skimmer cups, filter bags,pumps) in hard to reach
  • Not preventing salt creep/plumbing leaks.
  • Not using a GFCI.
  • Not mounting plugs/power strips above water level and/or
    use ‘drip loops’. I still see experienced reefkeepers
    do this from time to time.
  • Purchasing animals when one is unaware of what the care
    requirements are, how large the animal gets, what it may or may
    not eat, or even what it is. Research before buying!!!

— Matt_Wandell

  • Only top off with freshwater, not saltwater.

— rcsheng

  • Investigate the eating habits of your animals, before you
    bring them home.

— Illflyaway

  • read, read, read…..
  • put your hands on the products you want to buy… if you
  • get a account before you buy anything…
  • be humble… books don’t teach you everything…

— LA-Lawman

  • Not making enough of an effort to buy captive bred
    organisms, rather than wild caught.

— Entacmaea

  • A GFCI is a Ground Fault Circuit Interruptor, it is a type
    of electrical outlet that you see most commonly in kitchen and
    bathrooms- around water- that will automatically break the
    circuit if a surge is detected, to protect electrocutions due
    to water.
  • RO is Reverse Osmosis, a way to purify water. A way to get
    very clean water for your tank is to purchase a filter that
    uses RO and DI, or Deionization. An RO/DI filter usually comes
    in 4 -stages, a carbon filter, mechanical filter, RO membrane,
    and a final DI cartridge.
  • As for buying captive bred- most stores do not breed their
    own fish, but often sell fish that are tank-raised, and also
    could sell corals that are tank-raised by other aquaculture
    companies. Nowadays, many fish and I would estimate at least
    75% of all corals can be purchased as propagated, tank-raised
    specimens. Live rock and sand are also available in farmed
    versions. In my opinion, it is grossly irresponsible of a
    hobbyist to purchase a wild-caught specimen if there is a
    tank-raised equivalent available- especially with the state of
    reefs today-even if it costs a little more. Moreover, we should
    think twice about choosing organisms for our tanks that are not
    aquacultured- it should be one of the guiding principles when
    starting a new tank.

— Entacmaea

  • Trying to start off with cheap equipment and later upgrade
    to better stuff is a big mistake. You end up spending a whole
    lot more money in the long run and likely underestimating how
    bad your equipment really is.
  • Ask an experienced hobbiest which products to stay away
    from, because there is trully a lot of snake oil out
  • Before you do anything else, make a budget on what you can
    spend and what it will cost to set up a tank. Virtually all
    newscomers grossly underestimate what it costs to have a reef
  • For limited budgets, start with FOWLR and a really good
    protein skimmer, then when you are ready, make the jump to a
    good PC, VHO, T5, or best: metal halide light fixture.
  • Read all back issues of Advanced Aquarist & Reefkeeping
    Online Magazine. By then you may have enough knowledge and
    experience to attempt to keep corals.

— brandonberry

  • Not doing water changes during the cycle and allowing
    ammonia to climb so high it diminishes the critter diversity in
    the live rock.
  • Stocking too fast.
  • Using Tap water “just to start”.
  • Overstocking by not considering the adult size of the
  • Not researching the needs of the livestock.
  • Trying to fix problems using bottled additives.
  • Trying to build a reef tank on a Guppy budget.

— Guy

  • Not calculating enough flow and having the “I’ll
    get a pump later” mentality. By the time you do get
    pump(s) to fix the flow issue your LR will have detritius built
    up on it, probalby nuisance algae, etc. Things like lighting
    can be added later as coral demands need it, but flow is
    something that is important from day 1.

— sfsuphysics

  • Not buying the proper equipment the first time.
  • Listening to the guy or gal at the LFS.


  • Buying the cheapest tank instead of the right tank.
  • Buying a fish or invert on impulse.
  • Thinking that my fish would be the exception in its dietary
    needs then having it eat my corals.

— Oceans Ferevh

  • Not sizing the sump large enough to account for water
    drainage from the display tank during power outages or pump
  • I don’t know how many times I’ve heard people say
    “wow, the display tank’s water level is that low when
    the pump is off!”

— SciGuy2

  • Listening to opinions from too many sources.
  • Trying to cut corners on equipment.
  • Having too much Bio-filtration.
  • Having too little mechanical filtration.
  • Not having adiquate UV Sterilization.
  • Misadjustment of my Protein Skimmer’s gate valve.
  • Not keeping a balanced livestock diversity. IMO balancing
    the ecosystem is key to having a healthy reef.

— HisKid

  • Not keeping freshwater fish first. I have had several
    people see my tank and want one at home. A few have gone out
    and bought a set-up…sold the set-up because it is too much
    work. I tell everyone who has never kept fish to do freshwater
    for 6months to a year so you get an idea of tank maintaince,
    ect ect. During that time READ, READ, READ!!!

— Rob Top

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