The prawn has been used by some people as a form of ammonia production. Beneficial Bacteria (BB hence forth) use ammonia as a food source.
A decomposing prawn can generate a LOT of ammonia, but it's nasty and stinky. I prefer flake fish food. Add a pinch in and let it decompose.
@CurleyJones321, You are going about cycling a new tank , not wrong, but inefficiently.
BB need a few things to grow and thrive in a new tank.
Heat - we all know bacteria thrive in warmth. turn the temps up to 28degC.
Oxygen - flowing water. This is easy since it's taken care of by your pump/filter.
Alkalinity - BB colonies grow faster in high alkalinity compared to acidic water. So keep pH above 7.0.
And Food - in the form of ammonia.
So rather than use RO water remineralised to TDS 165 by mix tank and RO water together, just use ... wait for it ... tap water. If you have tap water like most countries in the world, it will have ammonia in it, with pH close to 8.0. Of course, you need to remember to dechlorinate it. Tap water has 2 of the 4 things BB needs. Just add the pump for water flow and heat. Yes, tap water has its uses, but we will be draining it after cycling is done.
Give this a few weeks, and once you see pH drop below 7.0, do a water change with dechlorinated tap water and add a pinch of flake food (or that prawn). This should bring the pH up again, and adds more ammonia food for the BB. Keep testing ammonia, nitrite and nitrates during the course of cycling. When you see ammonia and nitrate at zero with high nitrates, your tank is cycled.
At this point you drain the tank of 99% water (making sure the filter media stays wet) and add your RO water remineralised to the required TDS levels. Use this time before adding livestock to adjust pH, GH, KH and TDS.
If the tank stays empty after it has cycled, you need to keep feeding the BB with ammonia, this is where the prawn comes in handy. You need something to decompose in the tank, but is easily removed once the tank is inhabited. You have to remove it or ammonia is produced constantly.
Don't add bio boost or other bottled bacteria if you have a mature filter media you can wash in the new tank. Bottled bacteria will compete with the real BB, slowing down the multiplication of the real BB. The BB in your mature filter media or old substrate is the bacteria you want.
Hopefully those are some tips you can use for cycling a new tank.
(60cm * 30cm * 5cm) / 1000 = 9L ?
5cm substrate height for a 2footer is a lot, just saying.