Hello.
I'm having a hard time trying to find conclusive info on how much to fertilize new plants.
I have re-scaped my tank with new soil and new plants (filters are old so no nitrite issues).
Question is how much fertz to dose the fist few weeks?
Tropica website says no fertz first 3 weeks.
My local 'expert' says half dose first 2 weeks.

I assume dosing fertz in the beginning should be done carefully as new plants doesn't grow much and not using that much nutrients.

Wouldn't it be more correct to dose after some desired values like 20ppm NO3, 2ppm PO4 and so on?
I assume values should be same for newer plants and established plants?

By soil, do you mean you used something like potting soil?

Depends on the substrate you have. If the substrate is nutrient rich like soil or Aquasoil etc. then it should provide enough for the plants' needs.

However, I found the plants grow better and I have less issues when the plants are provided with all they need from the start. They might not consume the same as when they are fully adapted but they don't hurt if nutrients are there. Just the way I run my tanks.

Using Tropica Soil.
However alot of new/small plants have very few roots. I have been using fertz from the start, and tests show around 5-10ppm NO3 and 0.5ppm PO4 etc, so at the low end, showing plants are using most up.
I guess I'll up the dosage till I hit about double ppm. @dukydaf - You're right, it can't hurt

Too many ferts in a "new" scape can cause issues with algae.

New plants need time to transition and since you've noted that they don't have much in terms of roots, overdosing them with food can cause lots of headaches.

If you're tank is crammed with plants, overfeeding may not be a issue. If you only have a few, keep a eye on things.

@Smooch That's a good point.
I'm trying to explain that if you dose everyday, and the values for tests shows nutrient values are consistant it should be because of plants using up the nutrients added. As I understand algea rarely comes from too many nutrients but primarely due to dying plants/leaves which leaks glucose.
I little algea has actually begun to show and I it can't be too much fertz.

If you say so.

In order to know what is too much / versus too little would mean you would have to test your tank daily. If the plants are using / storing what they are being fed, you should come up with zeros with test results every time.

You have a 'new' tank which hasn't had time to establish. The bacteria in the new substrate needs to grow so it can break down the ferts, just like the roots of your plants need time to grow. I know companies like to promise 'instant' everything, but that's not how it works.

Algae doesn't show up out of nowhere for no reason, and it isn't just dead leaves that causes it.

Very true, there's not much bacteria in the gravel at this point. However I have 2 large established canister filters, and since no NO2 or NH3/NH4 is present, it seems I have enough bacteria in the canisters to keep up.
I test my tank every otherday (new soil plants are growing nicely), and it's been 10 days since startup.
Algea could be a lighting issue as I have new LEDs installed and not familiar with these yet.
Fertz added should not need to be broken down before plants can't absorb it...but ofcourse any leftover food, plant parts etc. needs to.

I never trust companies with any promises, and my fertz are calcutated and mixed from what my tapwater holds for the same reason.

I cut and pasted my post from another thread as it has some application here...new tank and ferts:

I will tell you my own issue which is similar. Set up a 24 gallon cube a month ago; Flourite substrate with volcanic pebbles on the bottom, CO2 through a GLA regulator (1-2 bps)/Finnex Ray2 light both on 10 hours a day, full planting of dwarf baby tears up front, hair grass in the middle and variety of taller plants in back. Didn't use ferts for a week or two and my plants started to look like yours, yellowing and some spots on leaves etc. Based on recommendations on the planted tank forum, picked up clay capsules with macros and Thrive all in one liquid fert from NilocG. First couple of weeks didn't add anything but the clay capsules below the rooted plants. Couple of weeks in I added the Thrive as directed...next day hair algae hanging all over the place. Over the last two weeks I have altered dosing and CO2 (cutting back both), changed out the water and cleaned off the algae twice, used H202 on the large rocks and baby tears (under water) to oxidize remaining algae...and tried again. I'm now down to one squirt of Thrive (recommended dose is one squirt per ten gallons, so I'm now down to less than a half dose) and also cut three times a week as recommended down to twice. I can't completely get rid of the algae but is is less than before. Chemically my nitrites are spiking and have been for over a week, and nitrates are starting to rise as well. I"m convinced the capsules, in combination with the Thrive in the water column with plants that are not fully grown...is simply too rich for my tank yet...particularly in light of the fact the tank has yet to fully cycle.