How to Start Feeding a New Planted Tank
When to start dosing, how much to use in the first weeks, and what’s normal while a new planted tank settles in.
The first six weeks of a planted tank decide how the next year goes. Plants are adjusting to life underwater, the filter is still maturing and algae spores are looking for a gap. Getting the plant food right from day one gives your plants the head start they need to outgrow the algae.
When should I start using plant food?
Start in the first week, as soon as the plants are in. It’s a common myth that you should wait until the tank has cycled. The plants need feeding whether the filter is mature or not, and healthy, fast-growing plants actually help a new tank settle by using up ammonia and nitrate.
The one exception is a tank set up with fresh, nutrient-rich aquasoil. Some soils leak ammonia and nutrients for the first few weeks. In that case, start at a quarter to half dose and build up as the soil settles.
A simple first-six-weeks plan
| Week | What to dose | What to do |
|---|---|---|
| 1–2 | Half dose: 0.5ml macro + 0.5ml micro per 10L daily | Big water changes (50%) two or three times a week. Short light period of 6 hours. |
| 3–4 | Build to the full dose for your light level | Water changes weekly. Increase lights to 7 hours if plants look healthy. |
| 5–6 | Full dose, adjust for any signs | Settle into your routine. Lights up to 8 hours. |
These are starting points. Low-light and shrimp tanks stay at the half dose for longer. See our dosing guide for every tank size.
What’s normal in a new tank
Some leaves melting
Most shop plants are grown out of water. Their old leaves often melt as the plant switches to underwater leaves. It’s normal. Read more in why plants melt.
Brown dusty algae
Diatoms (brown algae) almost always appear in weeks two to six. They fade on their own as the tank matures. Nerite snails and Amano shrimp clear them quickly.
Cloudy water
A bacterial bloom is common in the first fortnight. Keep up water changes and it clears.
Slow growth at first
Plants put energy into roots before leaves. Expect little visible growth in the first couple of weeks, then a jump.
New plants can’t use strong, long light yet. Extra light with nothing to use it is exactly what algae needs. Build up the hours as the plants start growing.
Adding shrimp or fish
Shrimp should wait until the tank is fully cycled and stable, usually at least four to six weeks. If shrimp are your goal, make sure your plant food is copper-free from the very start, because copper can build up in the substrate and filter. Our guide is aquarium fertiliser safe for shrimp? explains why.
Mistakes to avoid
Dosing a big weekly amount. A new tank can’t use it, and the surplus feeds algae. Dose daily instead.
Skipping days. Plants can’t store food. Missing several days in a new tank often triggers algae.
Too few plants. Plant heavily from the start. More plants means more competition for algae.
Chasing every algae spot. Some algae in a new tank is normal. Keep the routine steady and let the plants catch up.
Quick answers
Can I add plant food before the tank has cycled?
Yes. Plants need feeding straight away, and healthy plants help the tank cycle by using ammonia. Start at half dose in the first fortnight.
Should I dose plant food with aquasoil?
Usually yes, but start at a quarter to half dose for the first few weeks because fresh aquasoil releases its own nutrients.
How long before plants start growing?
Most plants show new growth within two to four weeks, once they’ve settled their roots and switched to underwater leaves.
Is brown algae in a new tank caused by plant food?
No. Brown diatoms are caused by a new tank’s water chemistry and fade as it matures. Keep dosing as normal.
Products mentioned in this guide
Everything to start dosing on day one: pre-measured macro and micro compounds, two 500ml bottles, two dosing syringes and a full dosing guide.
Already mixedMacro and micro solutions already dissolved and ready to dose. No preparation at all.
Shrimp safeThe copper-free trace element blend for your micro bottle. Safe for shrimp, snails and other invertebrates.
Copper-free aquarium plant food.
Dose on day one.
Pre-measured compounds, bottles, syringes and a full dosing guide. Shrimp safe, made in the UK, free UK delivery on every order.
Everything you need to get the most from your planted aquarium.
