With fish, you will add about 1/4 teaspoon of KNO3 once a week
Add mainly algae eaters for the first month or two(longer is better).
This will add about 3ppm per week.

A max light/CO2 tank will use at most 20-30ppm per week.
So you will see that the dosing frequency and the amount has been reduced.

Adding more will do no harm, but the issue becomes one of build up.
Unlike a CO2 higher light method, there are no water changes here.
That is the balance you are dealing with.

So you can add and estimate the uptake and error slightly on the lower side.
If you do this in a high light tank, you have the potential to make more mistakes.

Less light/no CO2 means much slower growth rate, so there is less NO2, PO3, Trace element demand from the plant and they do not shut down and stunt quickly.

So weekly dosing works fine, adding just enough works fairly well.
Recall DW suggest fish waste alone is enough for the plants.

While true with hardier species of plants, many cannot be grown well doing this. Well, if you add SEaChem EQ and KNO3/KH2PO4 this is simply no longer true.

The plants grow 5-10x slower, but they do grow.
Now you can test the NO4/PO4 for signs of build up if you calibrate the test kits and they appear to be accurate and dose based on uptake, but since the growth uis slow, generally the plants themselves tell you when you need to dose or how much/add more etc.

Most of you already know what NO3 deficent plants look like or K+, traces etc, so you'll see the same types of things with non CO2, just slower.

So, add 1/4 of the KNO3, 1/8 of the KH2PO4, SeaChem EQ -1/4-1/2 teaspoon each week and if you forget one week, that's likely okay too.
Note plant health as your test guide.

I prefer the SeaChem EQ and the macro's alone, I use onyx sand with leonardite+ mulm.

Do water changes only if you uproot and replant and need to really clean.
Use a brine net to remove leaves, mulm etc and swipe the net through the tank once a week to keep it looking clean.

You can scale things down for a smaller tank.
Sinmp,y divide the teaspoon measurements into 1/4 units for the 20 gal and recall these amounts, if you are off a little, that's fine.

If you want to use smaller units and be more accurate, make solutions and dilute the macro's in there. If you prefer testing once every 1 to 3-4 weeks, that's fine also, that's not much testing really and it serves a purpose should something seem odd, otherwise not testing generally gets you far.

Just use the 10:1 or 7:1 dosing ratio for CO2 : non CO2 tanks.
CO2 : Excel dosing 3:1 and with low light 1.5:1.

These are rough estimates, so some tweaking can be done, they are general guidelines to get folks hitting their target ranges without causing the plants to become severely stunted and in most cases these ranges will provide excellent growth, certainly much better than mere fish food alone will provide.

What are excesses? I'm not sure. Same for the CO2 tanks except with respect to NO3 perhaps and CO2, but we don't add CO2........so...no need to fret over that one.

But you can pruge the tank's NO3 by not dosing for a week or two, you do not need to do the water change to lower things. Just let things go for awhile and see.

As always, pack the tank from day one, add mulm and a good substrate(this will pay for itself!!!!!!!!!!!!!).

Adding a porous substrate like Floruite or Onyx sand will increase the waste cycling breakdown rates allowing better growth and less algae, since the main waste products are NO3/NH4, keeping NH4 down is well worth it and more bacteria are present on porous substrates.

So they will help add traces and help the cycling over the life of the tank, adding soil only last 6-12 months tops.

We can dose the KNO3/PO4/K+/GH and add fish food to supply what the soil will and dosing weekly is not tough.


Regards,
Tom Barr