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I've started my AP system on the 4th of September - the system is still cycling (with fish- tilapia). I've had a difficult time keeping my pH down, it's around 7.6 - 7.8. I've been using muriatic acid daily in very small amounts but maybe I should increase the application? Nitrite levels started climbing late last week and are above 5ppm (my test kit stops at 5 so I'm not sure how high the nitrites are). I dissolved 3 cups of aquarium salt in a 5 gal bucket then poured the salt mixture into the sump (275 gal tote).  There was no immediate lowering of the nitrites. I will add more salt later this week if the nitrites continue to be high.The daily water temps are between 72-82. I planted the gravel GB immediately but the plants are growing very slowly - they are surviving. I've been adding Maxicrop Seaweed daily to provide nutrients for the plants. My ammonia levels are around .25 ppm. There are increased amounts of nitrates in the system so I'm hopeful the cycle is getting close to completing.

The 50 tilapia fry and 6 goldfish are doing very well and have a big appetite although I'm trying to hold back on the food until nitrites fall a bit.


Any suggestions or comments are welcome especially ideas for bringing down the pH, ideal water temperatures during cycling, how long the fish can survive with high nitrite levels? I'm currently capturing some of the precious Southern California rain fall and may attempt a 1/3 water change if I can't control nitrites.


Trying to be patient. Russ

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Hi Russ,

You know exactly what you're doing here. The source water with high carbonates are not a problem. Usually in cycling we don't focus on the PH as much as this tends to lower itself over time, at any rate 7.6-7.8 is a normal range for now. Your temps are great for cycling. This is the critical point as you know when Nitrites peak, and as you can't register a reading with your kit, its wise to stop feeding at this point. Within a couple of days you should be in the clear, so keep posting readings daily until then. When I was cycling i worried myself to death, had trouble sleeping, and everything turned out OK just as yours will

Yep, the salt won't lower nitrites, it is only to help protect the fish from the nitrites a little bit.  Hang in there, sounds like you are about 4 weeks on and impatient about how long the nitrite spike is lasting (this is rather normal) the nitrite spike is the harder one to get past.

Resist the beggars and with hold feed as much as possible till that nitrite gets down.  It shouldn't be too much longer.  Cycling with fish usually takes about 6 weeks.  I expect you may see a sudden drop in nitrites along with a drop in pH in the next week.  Rain water will help in letting your pH drop lower as long as your media isn't causing the buffering on you.  I have hard well water but when I can top up with rain water my pH will come down.


How did you know I was feeding the beggars???? When I go out to the FT the tilapia fry actually jump out of the water at me wanting food although I would like to think they are just happy to see me.

Thanks Harold and TCLynx for the feedback.

TCLynx said:


Resist the beggars and with hold feed as much as possible till that nitrite gets down.

Soo hard to resist when they beg.  One of the reasons why cycling with fish can be difficult.  Hang in there.

pH dropped to 7.0 today, nitrites are still >5ppm, nitrates are around 10ppm, ammonia is between .25 - .50, no feedging..couple pictures:

Hi Russ,

Your nitrites are still peaking but they will soon drop as you are aware. It could be well above the 5ppm as you mentioned the test kit is restricted. At your temps it won't be much longer so continue daily testing and withhold feeding for now

How long can finger size tilapia go without food?

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