Have you double check your nitrite test? It could show wrong figures
The nitrification cycle works in two stages with two different type of bacteria. First step ammonia/ammoniac to nitrite, second step nitrite to nitrate. In the start it often happens that the process stops between the two steps and nitrite will be accumulated. Really why this happens is not completely clear – it’s like it exist a trigger point for the second step to start.
However this has a very little effect if you are running a seawater system. Nitrite is not very toxic for saltwater species of fish. The reason for this is that nitrite is picked up through the gill (probably trough channels in the cell membrane). But concentrations of chlorides in the water as low as 70 – 80 ppm will block this uptake. Normally sea water has a chloride concentration of around 19 000 ppm. Even in freshwater you can stop the uptake of nitrite through adding around 15 ml of table salt per 100 litre water.
If your test still show around 0.25 – 0.5 ppm and that you relay on your test you should NOT add any more ammonia – if you should add anything at all – add bacteria from the nitrospira or nitrobacter genus. I´m from the old Swedish school of nitrification and still believe nitrobacter to be the most common bacteria in the second step. This genus you can find in the upper soil segment in a nearby forest. I have started aquarium with water filtrated through forest soil. Just take two hands of soil in a bucket and add water. Mix. Filtrate through a coffee filter, put the filtrate (water) in the chiller and add some every day for the first 3 weeks. You can also squeeze a filter from another aquarium – fresh or salt does not matter – dilute it with some water and add the mixed liquid each day for a couple of week.
To say that using a fish in the cycling process is cruel - is for me totally wrong.
If you do the thing right you do not use the fish to indicate good water or not – you use the fish to produce ammonia for the cycling process. If an aquarium is new started it has no organic matter, no bacterial production of ammonia will occur – the fish is the only producer of ammonia. And how much it will produce depends on how much you feed him/her. You will control the ammonia production totally through your feeding regime.
The way I have started the nitrification process in a countless number of aquariums (and recirculated fish farms) has been (for the aquariums – the fish farms need a little more fishes :) ) to get a fish that is well feed and that will show up in the tank. My favourite for saltwater is the maroon clown. I put in my decorations, gravel and other things - mix the water – wait one day and add the fish. The first week I feed the fish 3 or 4 adult artemia (frozen) every THIRD day, not more. Second week I give the same amount every SECOND day and the third week – same amount EVERY day. After the fourth week I slowly rise the feeding and amount of fishes. I also add bacteria (commercial nitrification bacteria – no mix with “benefit” bacteria that normally are heterotrophs that will concur with the nitrification bacteria about space - or bacteria from sources describe above).
After three or four days I add my clean-up crew (before the algae population has grown to large) and I also introduce some hardy corals. I use a large numbers of cleaners – and as many species as possible. In my 300 litres DT I have around 100 + of different snails, 40 + of hermits (different species), one sea cucumber, one diadema urchin, three sand sea stars and some crabs
Note - corals are consumers – not producers - they will not rise the biological load – instead they will help to reduce it. I also use living sand, living rocks (for the hitchhikers) and after a week – I use to add some nitrates (1 – 3 ppm). I do not clean or prepare my living rocks – the phosphorus they bring with is what the tank need in the start to give a living ecosystem in a couple of months. And the organics and algae they content is food for my clean-up crew in the beginning.
For the notes – I have never lose a pilot fish, I seldom read any ammonia or nitrite. As I stated earlier – nitrite is not a problem in salt water. I have neither get any algae attack in the start.
Sincerely Lasse