A Cycling Question

[JMcQueen]

Im currently in the second month of cycling a 120L tank with a fluval U4 filter. The filter is still taking 24 hours to process 4.9 parts of ammonia and I was wondering if the mode of the filter would make any difference?

For those not familiar with the filter, it has three modes. The first mode is a full power jet out of the top nozzle which results in a great deal of surface movement and turbulance within the water. The second mode is having the spray bar in the middle running which gives a decent amount of surface turbulance and also in the middle of the tank. And then theres the third mode which results in deep water turbulance but virutally no surface agitation.

Therefore the question is, is there a water condition that lends itself to cycling more than an other? Does a highly turbulant water flow mean more through put and thus quicker processing or does the calmer water mean that its easier for bacteria to develop.

Alternatively, it the case that it doesnt make the slightest bit of difference.

 

[OldMan47]

Any operating mode that does not promote surface agitation is not one I would use for cycling. A cycle needs two things before it will happen. The first is the ammonia or nitrite, depending on which part of a cycle you are analyzing, must be present in he water at the filter. The second part, which is seldom addressed is that the bacterial colony in your media must see its chemical along with adequate oxygen. If the flows are too low to deliver the chemical the bacteria want, they will die back to the levels that are supported by your chemistry. The oxygen content of the water is determined by two factors. First is that the water must come in contact with the surface water of the tank for oxygen to be able to be absorbed by the water from the atmosphere. The second factor is that the water's oxygen must not be already maximized by other factors. That means that a decent flow of that oxygenated water must be taking place near the filter media being cycled.
I find that as long as my filter flow disrupts the surface of the tank, enough flow is happening in that area and as long as the tank is not already fully cycled, the flow of nutrients such as ammonia and nitrite are also being met simply by moving the tank's water.