NilocG Aquatics Liquid NPK+M 500ml Concentrated Aquarium Plant Fertilizer Review (2026)

Who this fertilizer fits

NilocG's NPK+M is built for planted tank keepers running the Estimative Index, or EI, dosing method, where nitrate, phosphate, potassium and micronutrients are dosed on alternating days at levels well above what plants strictly need, with a large weekly water change resetting the tank before the cycle repeats. It suits demanding, higher light or CO2 injected tanks where plants are growing fast enough to need that steady nutrient supply, and it works well for keepers who already dose dry fertilizer salts and want a liquid alternative with the mixing done for them. Someone running a low tech tank with slow growth, or who wants to dose once and forget it, is likely to find the EI routine more involved than they want.

What is in the bottle

The NPK+M name describes the contents directly: nitrogen, phosphorus and potassium macronutrients plus M for the micronutrient trace elements, combined into one concentrated 500ml pump bottle rather than split across separate macro and micro bottles. NilocG's own EI guidance calls for dosing on alternating days, for example micros on Monday, Wednesday and Friday and macros on Tuesday, Thursday and Saturday, with a roughly 50 percent water change on the seventh day to complete the cycle. Because the formula is concentrated, a little goes a long way per dose, and the pump top bottle is designed to dispense a consistent, repeatable amount each time it is used.

Dosing it correctly

Getting good results from an EI-style fertilizer depends on following the dosing rhythm rather than guessing at amounts, since EI intentionally overshoots plant needs and relies on the weekly water change to prevent nutrients from building up to levels that encourage algae rather than plants. Lower light or lower tech tanks generally need less frequent or less concentrated dosing than a high light, CO2 injected tank, so the schedule should be scaled to the tank rather than applied at a single fixed rate everywhere. Keepers new to EI dosing typically start with a documented weekly routine and adjust the amount up or down over a few weeks based on how plants and any algae respond.

Bottle life and value

Because the formula is concentrated and dosed in small pump amounts rather than capfuls, a single 500ml bottle stretches across many weeks of regular use on a small to mid-size tank dosed several times a week, which keeps the cost per dose relatively low compared to buying pre-diluted, ready to use liquid fertilizers. Larger or more heavily planted tanks that need bigger or more frequent doses will draw down the bottle faster, so actual longevity depends heavily on tank size and how aggressively the EI schedule is being run. Buying the fertilizer alongside a proper pump top dosing bottle, sold separately by NilocG, makes repeat dosing faster and more consistent than measuring with a cap.

Verdict and who should pick something else

This is a solid choice for anyone already committed to EI dosing, or ready to learn it, who wants a concentrated combined macro and micro liquid rather than mixing dry salts by hand. It fits demanding planted tanks with strong light or CO2 injection where nutrient uptake is fast enough to justify the routine. Keepers who want a simpler, lower-maintenance approach, or who are running a low light, low tech tank without CO2, are likely better served by a gentler all in one liquid fertilizer dosed a few times a week without the strict alternating schedule and large weekly water change that EI depends on.

Frequently asked questions