The Planted Aquarium Blueprint — Fertilizer, CO2 & Lighting in the First 90 Days

The first 90 to 120 days of a planted tank are make-or-break. Get them right and you'll have lush, explosive growth with little to no algae. Get them wrong and you'll be fighting algae outbreaks, melting plants, and nutrient imbalances for months. In this video, Henry from Nature Aquariums breaks down the exact fertilization approach, lighting schedule, CO2 targets, substrate setup, and water change routine that the team has refined over two years of running planted tanks in the store — covering both low-tech and high-tech setups.

Substrate — Set It Up Right From the Start

If you're starting fresh, substrate choice matters. Henry's go-to is UNS Contra Soil — it's low on ammonia leach and performs consistently. All quality aqua soils (ADA, Contra, and similar) work on the same principle: highly ionic particles that act like a magnet, binding nitrate, phosphate, potassium, and trace elements to the grains where plant roots can access them directly.

A few rules on aqua soil:

Only use it where you're actually planting rooted plants. If you're doing an Anubias and Java fern tank, save your money — sand or gravel is all you need.
Do not cap it. The old Diana Walstad method of capping soil under sand was designed for topsoil, not modern aqua soils. These substrates work best when exposed to the water column — they continuously pull down floating nutrients and bind them to the grain where roots can reach. Oxygen also exchanges back up through the substrate as roots grow. Cap it and you lose most of that benefit.
If you want a sand look around the edges, use sand or gravel at the perimeter and keep the aqua soil in the planted zones — don't bury it.

Lighting — Start Low and Build Up Slowly

New tanks are not ready for full photoperiods. Here's the ramp-up schedule Henry recommends:

Months 1–2: 6–7 hours maximum
Month 2–3: 7–8 hours
Month 3–4: 8 hours
4+ months: up to 9 hours max — never more

Plants get fatigued beyond 9 hours and you gain nothing from running longer. More light early in the tank's life means more algae, not more growth.

PAR targets by tank type:

Low-tech Anubias/Java fern only: 20–30 PAR
Low-tech with swords and stem plants: 30–45 PAR
CO2-injected carpet/stem plant tank: 40–70 PAR (start at 50 max in the first 30 days)

Don't have a PAR meter? Ask your local fish store — many will rent one or let you bring your light in for testing. Your light manufacturer may also publish PAR data for different mounting heights.

Water Chemistry — GH and KH

Two parameters that planted tank keepers often overlook:

GH (General Hardness — calcium and magnesium): 4–7 dGH or 100–150 PPM
KH (Alkalinity): 3–5 dKH or 40–60 PPM

These ranges cover the majority of planted tank species. Get these stable and your plants and fish will both benefit. Henry covers how to adjust GH and KH in separate videos — check the channel for those.

CO2 — Pressurized or DIY, the Numbers Are the Same

Whether you're running pressurized CO2 or a yeast-based DIY kit, your targets don't change:

Minimum: 15 PPM CO2
High-tech planted tank: up to 30 PPM

How to measure without a CO2 test kit: measure your pH before CO2 starts (lights off), then measure again 3 hours after CO2 begins. A pH drop of 0.5 = approximately 15 PPM. A full 1.0 pH drop = approximately 30 PPM.

Critical warnings:

Match your CO2 level to your plant mass. A heavy Anubias/Java fern scape doesn't need 30 PPM — those plants grow slowly and can't use it.
Consistency is everything. Avoid spikes and crashes — this is the main reason Henry is cautious about DIY yeast kits. Going a week without CO2 after running heavy CO2 is one of the fastest ways to trigger black brush algae.
Always have a backup CO2 bottle ready so you never run empty and wait days for a refill.

Fertilization — What to Use and When

After two years of testing combinations on both low-tech and high-tech tanks, here's what Henry's team has found works consistently:

Start fertilizing from day one — but what you dose matters more than how much.

The three fertilizer categories:

All-in-ones (Easy Green, AP3) — NPK plus trace elements in one bottle. Good all-around fertilizer, but can overload nitrates in heavily stocked tanks.
Potassium + traces (AP1) — potassium and trace elements without adding nitrate or phosphate. Henry's go-to for the first 90 days.
Standalone nutrients (Easy Potassium, Flourish, standalone nitrate/phosphate) — for dialing in specific deficiencies once you understand your tank's baseline.

Why potassium first? Plants arrive from the farm with nutrient reserves. In the first month they'll use those up along with whatever nitrate and phosphate is in the water from the cycle and fish waste. The one thing consistently missing is potassium. The first sign of deficiency: stem plants start losing their bottom leaves — they look like little palm trees. The plant is reabsorbing potassium from lower leaves to push upward growth. Holes in leaves, brittleness, and transparency are all potassium deficiency signs — not fish nibbling.

Manganese is equally important and often overlooked. It's the core element of chlorophyll — essentially the blood of plants. Getting trace elements in from day one, including manganese, is critical to healthy color and growth.

How to dose for your stocking level:

Lightly stocked tank (betta, a snail): supplement with an all-in-one like Easy Green or AP3 in addition to potassium and traces — you need the extra nitrates and phosphates.
Heavily stocked tank: stick to AP1 or potassium plus traces only — your fish are already producing plenty of nitrate and you don't want to add more.
Always test phosphate — if it bottoms out, plants will stall even if everything else is right.

Dosing frequency matters more than dosing amount. Daily small doses dramatically outperform one large weekly dose. On display tanks, Henry uses dosers set to micro-dose throughout the day — algae never gets the chance to feast on a sudden nutrient spike. At home, aim for daily or at minimum 3–4 times per week. If your fertilizer says 2 pumps per 20 gallons once a week, split that into half a pump 4 times a week instead.

Excel / Easy Carbon — What It Actually Does

Seachem Excel and its alternatives (Easy CO2, Easy Carbon) are not carbon dioxide. What they actually do is strip the biofilm off plant leaves so plants can access CO2 that's already dissolved in the water more efficiently. Even non-CO2 tanks have dissolved CO2 from fish respiration, bacteria, and surface agitation — Excel just helps plants use it better.

Important caveats:

Some fish and shrimp are sensitive to Excel
Vallisneria and mosses are highly sensitive and will melt — do not use with these plants
If you use it, dose small amounts daily — not sporadic large doses
Works well as a spot treatment for black brush algae directly on affected wood or rock

Root Fertilization — Start at 90 Days

After the first 90 days, add root tabs. Two products Henry recommends:

Aquarium Co-op Easy Root Tabs — NPK-based, works in both aqua soil and sand/gravel substrates. Dose monthly.
AP Jazz — ammonium-based, designed for aqua soil only. Do not use in sand or gravel — there's nothing to bind the ammonium and it will leach freely. Dose every 2 months.

Specific root nutrients worth adding for certain plants:

Iron tabs for swords — swords are heavy iron feeders; iron-specific root tabs produce stronger, more vibrant color
Potassium tabs for stem plants — many stem plants like Ammania depend heavily on root potassium for coloration even though they also feed from the water column

Water Changes — Non-Negotiable in the First 90 Days

This is the part people skip and then wonder why they have algae. Water changes are critical in a new planted tank — even during a fishless cycle. Here's why:

Plants release organics and lipids as they transition from emersed (above water) to submersed growth. Old leaves melt, new leaves adapt — all of that produces debris and organics that feed algae.
Nutrient imbalances happen constantly in a new tank. A weekly water change gives you a clean slate so your dosing targets are accurate.
Young plant mass can't process nutrients as fast as a mature tank — excess nutrients sitting in the water column are an algae invitation.

Water change schedule:

No fish (fishless cycle, fully planted): 50% water change once or twice a week
Fish already in the tank: three 15% water changes per week — less stressful on fish, still pulls out organics and excess nutrients effectively

The 90-Day Blueprint — Quick Recap

Substrate: use aqua soil uncapped where you're planting rooted plants; skip it for epiphyte-only tanks
Lighting: start at 6 hours, ramp up slowly — never exceed 9 hours; match PAR to your plant types
Water chemistry: dial in GH (4–7) and KH (3–5) and keep them stable
CO2: target 15–30 PPM depending on plant mass; measure via pH drop; never let it run out
Fertilization: start from day one with potassium and traces; add all-in-one or standalone nutrients based on your stocking level; dose small amounts daily or multiple times per week
Water changes: weekly at minimum — 50% if no fish, three 15% changes if fish are present
Root tabs: add at 90 days; match product to substrate type

Video Chapters

0:00 — Introduction: why the first 90–120 days are critical
2:00 — Aqua soil explained: how ionic substrates work and why not to cap them
6:00 — Lighting schedule: photoperiod ramp-up and PAR targets by tank type
10:00 — Water chemistry: GH and KH ranges for planted tanks
12:00 — CO2: targets, measurement via pH drop, and why consistency matters
17:00 — Fertilizer types: all-in-ones vs. potassium + traces vs. standalone nutrients
20:00 — Why potassium and manganese come first in a new tank
24:00 — How to dose based on stocking level
27:00 — Dosing frequency: why daily beats weekly every time
30:00 — Excel / Easy Carbon: what it actually does and when to use it
33:00 — Root tabs: when to start, which products, and which substrate they work with
37:00 — Water changes: why they're non-negotiable and how often to do them
42:00 — Full recap: the 90-day blueprint

Bottom Line

There's no single magic product that makes a planted tank thrive. It's the combination of the right substrate, controlled lighting, stable CO2, smart fertilization, and consistent water changes — all working together in the right sequence. Follow this blueprint for the first 90 to 120 days and your tank will reward you with the kind of lush, algae-free growth you see in the best aquascapes online.

All of the fertilizers, substrates, CO2 equipment, and test kits mentioned in this video are available at natureaquariums.com — and don't forget to check the video for the discount code to save on your order.