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Macro Nutrients in a stocked Tank

1092 Views 2 Replies 3 Participants Last post by  elusive77
Just wondering if dosing with the big 3 (N,P,K) are necessary in a planted tank that is stocked with fish because wouldn't the fish and the food you feed them supply the plants the NPK they require?

Right now I dose with Seachem Flourish, Iron, Excel, Trace and P. I found that my plants did beautifully with Flourish, Iron and Excel alone but I thought I'd give the Trace and P a try just to see what would happen. I didn't bother with N and K because I thought those two would get supplied by the fish for sure but not sure for the P. The only noticeable difference that I found with the Trace and P was that my algae growth rate increased a bit but nothing out of control. I'm guessing it's the P that's causing the increase in algae growth.

So I've decided to just go with Flourish, Iron, Excel, Trace and I'm gonna give this Advance a try.

As a side note I did test my water parameters and the NPK checked out perfectly within parameters and in the proper ratios before I dosed with P.
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Much would depend on number of fishes being fed and how often, plant mass, plus light energy being used.(more light/more demand)
I do believe that N and P could easily be achieved for most according to EI ranges which are more than other dosing strategies.
I started dosing EI and noticed my Nitrate levels were getting too high, even with the water changes, and my fish were suffering. So I stopped dosing KNO3 and switched to K2SO4 to get my Potassium. I feel like EI or any dosing method should be just a starting point and then adjusted to each individual tank. If you've tested and your levels of N and P are already high enough, then no need to dose them. Just keep testing periodically to make sure they remain that way. And dose anything you're not getting already. Also, keep an eye on your plants. They will let you know if there are any deficiencies.
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