Rhetorical Tank cycling question

[discolicious]

I recently killed off all my bacteria in an established 20 gallon tank with two 4 in. discus in it. Prior to the "incident" I did daily partial water changes using RO water that was adjusted to a pH of 6. I'm trying to cycle the tank while the discus are still in it. After about 4 days the ammonia in the tank rose to a high level, but I was using one of the ammonia products that converts it to ammonium. But I also discovered (on line) that the low pH does the same thing (converts ammonia to ammonium). It has been 8 days now and the ammonia reads VERY high, but the fish are swimming, eating very well, and showing no signs of stress. I haven't done a partial water change in 3 days because I was afraid that it would slow down the cycling process. So... here's a rather silly question, but I am curious... if maintaining a low pH converts ammonia to ammonium, and it doesn't appear to have any effect on the fish even at high levels, and no nitrite is present, and the water is clear and I'm doing fewer water changes.. what's the point of cycling the tank and having to do what appears to be more work just to keep the nitrates / phosphates in control? Isn't it simpler just to cut the cycle off before all the other happens, keep the water low in pH and make a change less frequently? What is the long time risk (not that I'm planning to do it, but curious)? :confused:

[TURQ64]

The conversion to ammomium at lower ph is correct, BUT...nitrifying bacteria still need to consume it. and even at low ph, there's still some ammonia present. It all doesn't convert to ammonium. WC's aren't only about NH3, there are other toxins to consider....long time risk? Dead fish with damaged organs.

[Second Hand Pat]

Does a low Ph dull the harming effects of nitrites?

[Eddie]

Regardless of ammonia OR ammonium, the bacteria (nitrosomonas) will begin the cycle process. Nitrosomonas convert the ammonia/ammonium to nitrites, regardless of your PH/ammonium. The next group of bacteria begin to establish (Nitrobactor). This is a very dangerous time, regardless of your PH. Nitrites can kill your fish fast.

http://ezinearticles.com/?Nitrogen-Cycle-And-Aquarium-Cycling-Including-Nitrification,-Denitrification,-And-Cycling-Methods&id=328078

[Dkarc@Aol.com]

Does a low Ph dull the harming effects of nitrites?

Nitrite are harmful at any pH. Only chloride ions can help in an emergency (calcium chloride, potassium chloride, sodium chloride, etc).

[Eddie]

Something else to consider, is that Nitrosomonas will build faster/work more efficiently with a higher PH. With a low PH, they work slower/less effectively, thus making your cycle prolonged. Is there a reason why you are using RO water, maybe this is a breeding tank?

[discolicious]

Thanks Eddie,
I use RO water because I'm on well water and it is extremely hard. The pH is also close to 9.

[CajunAg]

I don't mean to go into a tangent, but isn't it true it's better to raise young discus in hard water? Something about the minerals and dissolved compounds actually helping the fish to grow better?

I've also heard that, at least for domestic discus, the pH isn't much of a concern (extremes notwithstanding), as long as your water quality (including pH) is consistent?

Sorry to the OP for not answering their question, my answer is in agreement with Eddie's

[Dkarc@Aol.com]

Keep in mind, if there is little or no alkalinity in the water (RO), the bacteria cannot process the ammonia/nitrite. I would strongly advise adding back some of the tap water to provide the alkalinity required. Also, as Eddie said, pH that is on the acidic side is not conductive towards bacterial growth. A combination of no alkalinity and a slightly acidic pH will give you the huge ammonia spikes. Given that the ammonia levels are very high, add back the tap water very slowly (days). You dont want to spike the pH and kill your fish due to high levels of unionized ammonia.

-Ryan

[Eddie]

Thanks Eddie,
I use RO water because I'm on well water and it is extremely hard. The pH is also close to 9.

I'd use an RO/tap mix in your case unless you are using the water for a breeding pair.

[atitagain]

Regardless of ammonia OR ammonium, the bacteria (nitrosomonas) will begin the cycle process. Nitrosomonas convert the ammonia/ammonium to nitrites, regardless of your PH/ammonium. The next group of bacteria begin to establish (Nitrobactor). This is a very dangerous time, regardless of your PH. Nitrites can kill your fish fast.

http://ezinearticles.com/?Nitrogen-Cycle-And-Aquarium-Cycling-Including-Nitrification,-Denitrification,-And-Cycling-Methods&id=328078

Thanks for the link Eddie, that was a great read. There was another good link that was updated on 4/18 that had additional information talking directly to low PH and the challenges it creates for the Nitrogen Cycle.

http://www.americanaquariumproducts.com/Nitrogen_Cycle.html