Do I need a protein skimmer? Is a mechanical filter OK?

If you have a small saltwater or marine tank, do you need a protein skimmer? Is mechanical filtration sufficient? It's a common question and here is the answer.

We've been running a 10 gallon nano saltwater aquarium for quite some time with just a Fluval Aqueon 30 filtering the water. It pulls out a fair amount of junk just using some filter floss. (We prefer to use fine filtering that also reduces the water flow of the filter to a small degree.) We bought a nice protein skimmer - the Tunze 9001 - which is a very compact unit. If you fit this protein skimmer onto the side of the tank, it limits the amount of space it intrudes towards the front of the tank and doesn't look terribly huge. But still, the skimmer takes up a very noticeable volume and we preferred not to use it. So... would water changes be sufficient?

Almost unanimously you can read around the Internet that regular water changes on small saltwater tanks are easily sufficient to combat the filtration of chemical waste in your aquarium. While the skimmer can pull out a frightening amount of junk, it's really not as high volume as it seems. A good amount can be reduced by using some chemical filter media in the mechanical filter (such as Seachem Purigen, which we use.) And while not exactly the same, the reduction of impurities in the water through a weekly 20% water change should be sufficient in nano and pico tanks. A protein skimmer is usually recommended on tanks that are 20 gallons or above. If you have a FOWLR (Fish Only With Live Rock) you can also get away without having a protein skimmer at this size. But if you run a reef with corals, you'll probably want to think about having a skimmer at the 20 gallon size and most certainly once you hit 30.

We also regularly change the filter media every week and certainly no longer than every 2 weeks. I'm not talking about the Purigen and filter media (we also sometimes use Phosguard, which is very helpful in reducing phosphates which cause algae growth and rise quickly in nano and pico tanks.) I'm talking about the filter floss and pads you may use. Perhaps we'll post some photos but, in short, turn your mechanical filter into something slightly different than intended. Don't use the stock filter pads and carbon. Use small amounts of filter media like Purigen in a Seachem "The Bag" which can be purchased for $8 and the amount of a stock package of Purigen can last you an entire year without refreshing. As a result, you really won't need and will forget about a protein skimmer - and you'll be happier without the fuss.