cycle with plant life

beaslbob

Well-Known Member
in this thread:
https://forums.saltwaterfish.com/vb/s...=1#post3214717
I stated that plant life like corralin algae and macros prefer to consume ammonia over nitrates and therefore it is possible to have a cycle where there is no ammonia or nitrIte spikes as long as there is sufficient plant life like algae on live rockes or macros in a refugium.
Perhaps I misunderstood but florida Joe expressed the very common believe that that is not true.
The usual ammonia->nitrIte->nitrate cycle is the aerobic bacteria action assuming no plant life (or anything else) is acting. This thread is to share my experience when plant life is present and thriving.
So as an example of a "planted" cycle here is a chart when I started a FW tank with plants. This tank was a 20g with no water changes, no mechanical filtration, and not circulation not even an air pump. Literally just the tank, substrate, water, plants, fish, and lights. So the only thing resulting is these parameters is just the fish and plants.

Before you dismiss this as a FW tank let me assure the same type of cycle is experienced in a marine environment. This tank even had a peat moss substrate yet was pegging the pH kit at 7.6. Using the api high range test kit the pH was actually 8.4-8.8. The high pH was due to the plant action lowering co2.
When reading the chart keep in mind the x axes is not linear as the last tick is several days.
The tank had been running fish less and heavily planted for a week before params were measured.
Notice that a fish was added on day 1 and another on day 15 and each time ammonia "spiked" up to .25 ppm then dropped down to 0 the next day. Also nitrates were 5ppm until day 21 when they dropped down to 0 also. What is happening here is the plants prefer to consume ammonia over nitrates. So when ammonia production from the added fish increased the plants started consuming the ammonia over the nitrates. Which resulted in some nitrates and the ammonia being controlled very quickly and in a day brought back down to unmeasureable levels. Then as the aerobic bacteria build up less and less ammonia was available for the plants so finally the plants started getting their nitrogen from the nitrates because that is all that was available.
One of the very important things in all this is the stability of the system. Say sometime in the future ammonia increases. The macros/plants would start consuming that ammonia preventing the dangerous ammonia spikes. One time on a marine tank I basically doubled to the fish load. The result was no measureable ammonia or nitrIte spikes but within 2 days nitrAtes had spiked to 20ppm or so. Then 2-3 weeks later nitrAtes droped down to 0. So the system with the plants/macros is much more forgiving of user errors.
This is the reason I stated that it is possible for a tank to cycle with no (or low) ammonia/nitrite spikes. Or at the most a safe spike in nitrates. If you have fully cured live rock with thriving algae or start the tank with a refugium with thriving macro algaes, that type of phantom cycle in fact is to be expected. If you get ammonia spikes that are above .5 ppm or so it simply means the algae was not thriving enough to completely balance out the tank and needs to expand.
Besides if just makes sense to me to recycle fish wastes (ammonia, nitrates, phosphtes, and carbon dioxide) into fish food and oxygen.
submitted for your consideration and discussion.
worth at most .02
 
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