Some Cycling-with-fish Questions

[rdd1952]

The pH is down again. Something's going on. No nitrite and only 1 ppm ammonia, so I'm holding off on the water change until I can get to the lfs this afternoon with a water sample.

I found this article yesterday and thought the following paragraph from it was very interesting. It may help explain why your tank isn't cycling.

"The pH is also a vital factor in nitrification. Maximum rates of nitrification occur at pH values above 7.2, peaking at 8.3 (a common pH for marine tanks) then falling at higher values. What surprised me was the rate at which the effectiveness of nitrification dropped in acidic pH values: to less than 50% optimal efficiency at pH 7.0, to just under 30% at pH 6.5, and to just over 10% of maximal efficiency at pH 6.0. At these low pH values, nitrifying bacteria don't die, they just stop metabolizing and reproducing. Of course in these acidic conditions, most of the toxic NH3 is ionized to non-toxic NH4. But I had been under the impression (and mentioned here) that the pH needed to drop quite low, below pH 4.8, more like the acidity of a peat bog rather than conditions in a home aquarium. Not so."

Driftwood will generally lower pH as will peat. The lower the KH (buffering capacity), the greater effect those things will have. I don't know if you have either of those or not.

What causes a drop in pH in aquarium water? Decaying organics? Would the heavy aeration be introducing CO2 into the water? I'll try turning the airpump down (it's currently running wide open.)

Actually, it's the opposite. Aeration drives CO2 out and oxidizes the water so it should actually raise the pH. People with planted tanks rarely run air pumps as it drives the CO2 that their plants need out.

You're right -- it's difficult sorting out advice! For example, I've heard people who've kept plecs say that the young ones are very delicate. I've also heard others say that plecs, even the juveniles, are the cockroaches of the aquarium world. Some people say the inch-per-gallon rule is a good one, others say that it's complete crap.

My understanding is that young plecs are more delicate but I have no personal experience with them. I inherited one from my son when he had to take his freshwater tank down. He is a hardy fellow as he lived for 2 weeks in my sons filter (long story).

I do believe the inch-per-gallon guide is exactly that, a guide. It's not etched in stone but is good for setting up a new tank. If you stay under that, you should generally not have a lot of problems once the tank is cycled. After the tank settles in, there is room for expansion if everything is going well and you have good filtration. The guide definitely doesn't apply with messy fish like goldfish, plecos and oscars to name a few. One of them creates the waste of 3 times the equivalent length in fish like tetras. So stocking is more like 1" per 3 gallons.

 

[tmack]

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I just noticed a newer member (tmack) on here who happens to live in the same area as me and by coincidence has worked 29 years with the same company that my wife worked 22 years for (different offices). We have communicated by PM and he was mentioning that he had been into fishkeeping for almost 50 years and that they never tested for ammonia or nitrite. They didn’t even know what they were.
[/quote]

Hahahahaha - you're giving away my age rdd1952! Yes - people these days don't realize how many good things are available to help with keeping fish. Back then we didn't have all the knowledge, or the high tech filters, huge tanks, and other nice equipment that's now commonly available and affordable. If you had a 10 or 20 gallon slate bottom glass tank you were doing pretty darn good. That many years ago no one in the hobby really even knew about cycling, and we didn't test for ammonia, nitrites, nitrates, etc. But, amazingly I never had any real problems with keeping fish alive, or even breeding some of the smaller cichlids like convicts & kribensis. An occasional outbreak of ich, and an (at that time) unexplained fish death once in a while, but for the most part the fish remained healthy. I'm still convinced that fish were hardier back then - a lot were wild caught and weren't the result of inbreeding over & over to get the characterstics everyone wants - increased color, long fins, etc. I think in a lot of cases we've removed the hardiness of fish by inbreeding, in favor of "prettier". The only place I see a "natural" guppy these days in in feeder fish tanks - kinda sad actually that the forerunner of all the fabulous guppies we have today is now just a feeder fish. Anyway, I'm starting to babble, so I'll just say that I'm really happy to have all the "stuff" that's now available to us, as well as increasing knowledge about the fish and fishkeeping. And I still learn something new and worthwhile every day in these forums. But I still have my own opinions on some of the "rules" that people set up for fishkeeping - I'll never consider myself an expert, nor will I think anyone else is. There are just too many variables in this hobby - what works for one of us may not work for others, but if the fish are kept healthy that's what matters most!

 

[Tessla]

I do think you're right there tmack, fish aren't very hardy right now. As little as ten years ago, even neon tetras were considered suitable fish for cycling, as were fancy guppies. In fact, I cycled with a couple of tetras and fancy guppies and didn't lose a fish. Sure wouldn't recommend doing that now.

I've kept a few plecos: one gibbiceps we purchased at an inch in length that got well over a foot, one common that we adopted at about a foot and got well over 15 inches (we had these guys for years and eventually gave them to a friend with a pond that stays warm year round), and right now I have a clown pleco that has been doing well for a few months. There were also at least four or five various other plecos that died for no apparent reason soon after being added to a mature tank with a regular maintainence sechedule that also housed a peacock spiney eel and various other much more delicate fish, never lost any of the more delicate fish. Add to that three gibbiceps that my friends have tried keeping in ten gallons (told them not to, nobody seems to believe how big they get), two died soon after being introduced to the tank, one is still surviving, all three were put in poor water conditions though none of them as bad as a cycling tank. They're definitely not the cockroaches of the aquarium world in my experience, I'd give that title to danios.

As for the inch per gallon rule, what rdd1952 is very true. It only applies to small, slim bodied fish and then only as a guildeline, but it's still useful if you're doing a typical community setup.

Note that in addition to peat and driftwood lowering pH as rdd1952 mentioned, ammonia is building up when you're cycling and the level is fluctuating as you do water changes. Ammonia is basic, so more ammonia will drive your pH up, less will drive it down hence pH fluctuations in cycling aquariums being very common. Your pH would likely be very stable if you had a mature tank.