Cycling not Backpedaling


Liz Collins has worked for a well-known national pet supply retailer since 1998. She’s also an avid and experienced aquarist in her own right.  For the record, she owns a 29-gallon fresh-water community tank and her current favorite fish is the pineapple swordtail.

Pineapple Swordtail

photo source

Having recently taken the opportunity to tap her expertise, I asked Liz what’s the biggest mistake most beginners make when setting up their first tank. Without hesitation she replies:

“Too frequent water changes. Too frequent water changes kill your tank’s nitrogen cycle.”

Ouch. What’s a nitrogen cycle?

“The nitrogen cycle is, basically, the life cycle of the beneficial bacteria living within your tank’s eco-system.  It keeps your fish healthy. It’s analogous to breast milk for a baby, providing nutrients, helping the immune system. It also breaks down parasites like the kind that cause Ick and other fish diseases.”

Ah, so changing out the water before that cycle takes hold…?

“Causes cloudy water…”

Which prompts another water change…which kills whatever beneficial bacteria were still clinging to life… which results in more stressed (possibly dead or dying) fish…which prompts another emergency water change… and you get the picture, murky as it is.

No? Still cloudy on the subject? Here’s an excellent, technical overview:

And here’s another:

In the meantime instead of ramping up a case of “new tank syndrome,” consider adding a chemical product (available at any pet store) to clear the tank quickly.

“Basically these products enlarge the particles in the water so the filter can filter them out,” explains Liz. “Plus, it’s not a chemical that’s detrimental to your fish. You certainly don’t want to rely on a commercial chemical for maintenance, but it will help you ride out the cloudiness as the cycle’s trying to establish itself.”

Liz reminds nitrogen newbies, “It can take a full two months for the nitrogen cycle to work its way through a tank’s system. You may still see cloudy water before that. You may or may not see algae.”

And you also shouldn’t see any fish before week two.

Because, in all honesty, you shouldn’t  add them before the cycle begins to take hold.

“Lack of an established nitrogen cycle causes distress,” continues Liz, “effecting gill functions, symptoms like fin clamping.”

Fin clamping’s when fish hold their fins tight to their bodies. It’s a clear sign of stress, physical discomfort.

“If you see fish in distress you’ll want to add aquarium (not household) salt (after following dosing instructions), and perhaps a water clearing product. But really, the goal is to not put your fish in jeopardy in the first place.”

Indeed, aquarium keeping is a lesson in patience. And more patience.

When you first set your tank up you want it to cycle on empty. Sure, go ahead and have fun aquascaping… putting in your gravel, decorations and plants – though live plants have needs too and that’s a whole ‘nother post! Install your heater and let your filter gurgle to itself for those recommended two weeks…


“That’s hardly ever done,” laments Liz. “You can’t even get people to wait two days sometimes.”

She suggests trying to counteract the effects of impatience by adding a chemical like ‘Cycle’ or some other biological media.

“It will initially make the water somewhat slimy,” continues Liz, “but that’s good. That’s your nitrogen and all of the good bacteria establishing the system.”

After you’ve added that product,  wait at least 24 hours before adding fish.  Liz maintains that even with jumpstarting the tank with “Cycle” it’s still better to wait two weeks.

Why wouldn’t you? Two weeks to do your best to establish the healthiest environment for your new pets … good for them and good for you.  A newly established tank full of clear water and energetic fish beats the murky alternative any day.

But, if you simply can’t wait..  consider some “starter fish.” Liz says, “Hardy Dalmatian Mollies can help cycle a new tank. Rainbows and pineapple swordtails, too. Basically any of your larger fresh-water fish. All good.”

Not so Cory cats.  Liz does not recommend any sort of bottom feeders. Algae eaters either. Try saying that ten times fast!

“There’s nothing to sustain them.  Not enough tank to clean or algae to clear.  You can feed them commercial pellets but that can make them lazy enough not to do their job.”

In an aside about algae eaters, common plecos in particular, Liz says the ever popular plecos shouldn’t go into anything less than a 55-gallon tank. “They might be an inch long when you purchase them but they can grow to be 18-inch adults.”   An observation, which leads to some parting advice:

Read the decals attached to pet store tanks. They’re there to help you identify each species’ temperament  (community or aggressive) and its environmental requirements. Labels should also indicate how large a fish is likely to get.

Liz flashes a bright smile. “The very first question I ask is ‘How into fish are you? Everyone wants to start with a five or ten gallon tank but when you start looking at the adult size of a particular fish you’ll realize you’ve limited yourself to two fish.  I always say buy the biggest tank you think you can maintain. And, the bigger the tank, the easier it is to balance the eco-system. When you have more volume in the water the fish can tolerate more toxic levels –  essentially, a bigger tank’s more forgiving of beginners’ mistakes.”

And beginner’s luck? Perhaps… but…

“Every day is a new day. It is better to be lucky. But I would rather be exact. Then when luck comes you are ready.”

Ernest Hemingway, The Old Man and the Sea



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