Plant fertilizer absorption rate?

[CA Dad]

Approximately how long does it take for plants to absorb liquid fertilizers? I assume it depends on the number of plants that are water column feeders, their immediate need for nutrients, and the amount of water in the aquarium. How about a lightly planted 30 gallon that just got several more water column feeders (to make the tank heavily planted) just a few weeks ago? Is it best to dose the tank after a water change? Is it okay to dose a day or two (or three or four) before a water change so the nutrients are not wasted? I assume adding the Easy Green All-In-One Fertilizer will not spike the level of ammonia in the aquarium.

I use tabs too, of course. I do not have water column feeders exclusively. 
 

 

[Cory]

I'm not sure there is an easy way to really answer this question. The best answer is, use something like Easy green as your fertilizer and nitrate source. When it gets below 10ppm, dose more. when It gets above 50ppm, change water. Anything in between, you're good to go without dosing more, or changing water. Now this is a very brief overview, but works well for many aquarists.

[KBOzzie59]

There is no ammonia in Easy Green (EG).  As for absorption and dosing it also depends on your lighting.

Yes dose after water change or else you just dump the EG down the drain.

There are timestamps in this video.

 

[Jungle Fan]

In regards to absorption time that's a question that really no one can answer for you, not knowing how many plants of what type you have, what type of light, how long a photoperiod you have set, and if you are adding CO2, or not and even then they would be guess-timating. If you really want to know it is best to get some water test kits and check for the presence of each nutrient separately over time. I haven't been that ambitious, or industrious since I finished my last microbiology research project in college a good long while ago.

To answer your question in regards to dosing after a water change, yes that is the general method. I do weekly 50% water changes on my tank and my weekly dosing regimen begins new the day I do a water change. I follow the instructions on my fertilizer so I'm generally done dosing a day, or two before the next water change.

If you don't have other issues with high ammonia levels, and follow the instructions on the Easy Green bottle in regards to dosing for your size of tank then your ammonia should not spike.

The root tabs are definitely the way to go for root feeders like Amazon swords, and cryptocoryne.

Here's a picture of my tank, in light of full disclosure I'm also using CO2 fertilization:

[PlaneFishGuy]

My recent experience with my first planted tank was that it took a lot more fertilizer than I thought to get up to 20ppm Nitrates. Once I achieved that it was pretty straightforward to getting the dosing right and a lot less fertilizer to maintain it. 

I was uncomfortable pumping more and more fertilizer (well above the directions on the bottle) but once I started trusting my test kit/strips,  I realized dosing up one pump at a time then testing and repeating made it pretty low risk of overdoing something. Once I got to 20 ppm I just tested daily to see how long it would hold; after about 2 rounds of adjustment I got it dialed in to where its a pretty predictable schedule/amount now. 

Again I am new so anyone feel free to correct; just stating what worked for me with trying to figure out the dosing amount/frequency for my specific set up.    

Edited March 22, 2021 by PlaneFishGuy

[Jungle Fan]

@PlaneFishGuySounds like you're doing the right thing, as long as you are watching the water parameters and keeping an eye out for algae. You should post some pictures of your tank.

[PlaneFishGuy]

@Jungle Fan I definitely let the algae get out of hand but once I got a little smarter on lighting I realized that was likely my issue. Had a Fluval Nano running too high and too long for the size of the tank and most of the plants. 

I was battling algae before I really had any detectible nitrates in the water and the tank is pretty heavily planted. I recently cut my lighting back and plan to keep water parameters stable at recommended levels and see if I can get the lighting balanced. lighting change is only in day 3 so Its still too early to tell. 

Again new tank and new planted tank owner so don't want to any of this to be misconstrued as advice. Just what I've seen in my tank so far.  

Honestly the last day the tank looked photo worthy was on day one 🙂  but Ill post some pics in another thread. Don't want to hijack from CA Dad discussion on fert absorption. 

[DShelton]

I have been searching through the scientific literature to help me answer the question about nitrogen uptake from the water column (which form NH3 or NO3) versus the substrate. I have found a couple of different papers, but so far have yet to find anything definitive.