If you got no ammonia reading, I would leave the tank alone and monitor it. If the nitrite starts to rise or you see the fish at the surface, you can add a bit of salt to the water or do water changes. To counteract nitrite one can use chloride to block the nitrite. Just add plain old salt, which is 2/3 chloride, to achieve a concentration of 10 times that of the nitrite. In water the ppm are essentially = mg/l, so we work with grams and litres. Lets assume your tank goes up to 1 ppm of nitrite. I count a 29 gal as closer to 95 litres, after subtracting for glass and decor:
1 ppm N02 x 10 = 10 mg/l x 95l x 1.5/1,000 = 1.425 gm. salt.
The 1.5 comes from needing that much salt to get 1 mg/l of chloride (2/3 of salt is chloride). The divide by 1,000 is to convert milligrams to grams. As you can see this is not much salt. I have an Ohaus triple beam gram scale and 1/4 level teaspoon of Morton's Salt weighs about 1.5 gm.
Note: The only way to remove salt from a tank is via water changes.
For those unaware 1/4 teaspoon in 29 gals is almost a trace amount compared to true sw for dips etc.
Salinity measurements. A 3ppT or 5 ppT (parts per thousand) salt solution is equivalent to 0.3% or 0.5% salinity, or
3 or 5 grams per liter, or
3 or 5 teaspoons of salt per gallon. This is the standard recommendation for salt treatment for skin parasites and for
Ich that you will find at
Doc Johnson's KoiVet.
from
http/www.skepticalaquarist.com/salt
The nice thing about this method is, in regards to getting the bacteria that might be missing back to strength, the salt doesn't affect the bacteria itself nor its ability to process nitrite. What is does is block the effects of nitrite inside the fish. This is an old trick used by bind keepers and aquaculture where water changes are not practical. This insures the shortest amount of time with nitrite readings before the bacteria can handle it all.