Do Heavily Planted Shrimp Tanks Need N and P?

 

A Gentle Look at Nitrate and Phosphate in Tap-Water Setups

If you only keep a few plants and feed your shrimp every day, you probably never think much about nitrate (N) and phosphate (P). Food and waste usually cover that part.

But once you move into a heavily planted shrimp tank – lots of stems, carpets, or fast growers – the question becomes more serious:

“Is my tank still getting enough N and P from food and waste,
or do I need to add a little fertilizer for the plants?”

This post looks at nitrate and phosphate in tap-water shrimp tanks, especially those with dense planting, and how to keep any dosing gentle and shrimp-safe.

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1. Quick Reminder: What N and P Do

You’ll see them written as:

• Nitrate (NO₃⁻) – our usual form of N

• Phosphate (PO₄³⁻) – our usual form of P

Very simplified:

• Plants use nitrate to build leaves and stems.

• Plants use phosphate for energy and strong roots.

If N and P are far too low, plants stall, even if Fe and K are okay.

You don’t need perfect test-kit targets. You just need “enough that plants can move forward”.

If you’re still getting used to GH, KH, TDS and what they actually mean for your water, you can read my earlier post on three water numbers that quietly shape your tank.

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2. Where N and P Come From in a Shrimp Tank

In any normal shrimp tank (Indonesia, Malaysia, anywhere), N and P mostly come from:

• Shrimp and fish waste

• Food (flakes, pellets, shrimp pellets) that is eaten and broken down

• Decomposing leaves, biofilm, and mulm

So even if you never touch a fertilizer bottle, some nitrate and phosphate are already cycling in the system.

In lightly planted tanks, this is usually more than enough.
In heavily planted tanks with careful feeding, plants can grow faster than the tank replaces N and P.

That’s when you start to feel like:

“My water looks clean, but plants don’t really move…”

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3. When Extra N and P Usually Aren’t Needed

Even with shrimp, you often don’t need extra N and P if:

• Plant mass is moderate: moss, buce, anubias, ferns, a few crypts.

• You keep fish with the shrimp and feed daily.

• Nitrate tests show some reading (for example 5–20 ppm), not always 0.

• Your main problem has been algae, not weak plants.

In this kind of tank:

• Food and waste often give enough N and P.

• Adding more usually just feeds algae.

Here it’s better to:

• Keep feeding and maintenance consistent.

• Focus on small amounts of Fe and K only (like in your “Gentle Fertilizing for Shrimp Aquascapes” article).

No need to complicate things.

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4. When a Heavily Planted Shrimp Tank May Need N and P

Extra N and P become worth testing when several of these are true:

• The tank is heavily planted – thick stems, fast growers, or dense carpet.

• Stocking is light – mostly shrimp, maybe a small group of tiny fish.

• You’re careful with food (no big leftovers, no “just in case” feeding).

• Test kits often show 0 nitrate and very low phosphate, even before water change.

• New plant growth looks weak, pale, or stunted, while old leaves slowly decline.

• Light is decent and you already give a little Fe & K, but growth still feels “stuck”.

In that situation, plants are not pretending – they’re genuinely hungry.

A small amount of N and P can:

• Help new leaves come in cleaner and stronger.

• Let plants cover surfaces faster, which can reduce algae later.

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5. A Simple Way to Check If You Really Need N and P

If you’re unsure, you can do a small “experiment month”.

Week 1–2: Observe Without N & P

• Keep your normal routine.

• Test nitrate once a week (before water change).

• Take a quick phone photo of the tank once a week from the same spot.

If nitrate is always 0 and plant mass is high, it’s a clue that plants + bacteria + water changes are using up everything the tank produces.

Week 3–4: Add a Tiny Amount and Watch

• Start an all-in-one fertilizer that includes N and P, or a very small dose of N/P solution.

• Use only around ⅓ of the label dose for your tank volume, once or twice a week.

• Keep everything else the same: light, feeding, water changes.

Compare:

• Do new leaves look a little healthier and larger?

• Does algae stay the same or get worse?

• Do shrimp behave normally?

If new growth improves and algae doesn’t bloom, the tank probably benefits from that small extra N and P.

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6. Gentle N & P Plan for Heavily Planted Shrimp Tanks

Here’s a calm starting routine for a densely planted, tap-water shrimp tank.

6.1 How to Dose

Choose one of these:

1. All-in-one fertilizer with NPK

   • Dose ⅓–½ of the recommended weekly amount for your volume.

   • Split into 1–2 doses per week.

2. Separate N & P solutions

   • Start with very small amounts, aiming just to prevent 0 readings.

   • For example, enough to raise nitrate by ~5 ppm and phosphate by ~0.2–0.5 ppm per week, then adjust.

Always:

• Keep your usual water-change schedule.

• Watch new growth more than old damaged leaves.

6.2 What “Success” Looks Like

You’re in a good zone when:

• Nitrate is not always zero, but also not extreme.

• Plants send out fresh, healthy new leaves.

• Shrimp graze and molt normally.

• Algae is manageable (normal for a planted tank, not taking over).

I also have a separate post on keeping shrimp without RO or distilled water, if you’re working with whatever comes out of your tap.

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7. N and P in Almost No-Water-Change / Natural Tanks

In deep-substrate, leaf-litter, “natural” shrimp tanks:

• N and P mostly come from food, leaves, and mulm.

• A lot of nutrients sit in the substrate and biofilm, not just the water.

• Water changes are small or rare.

In these systems, regular N & P dosing can easily be too much.

For growing extra grazing surfaces without overfeeding, you can also see my post on accelerating biofilm production for shrimp tanks.

It usually works better to:

• Feed moderately – enough for shrimp, not enough for a layer of uneaten food.

• Let leaves and roots act as slow-release fertilizer.

• If you ever test bottled N & P, do it:

  • In tiny, rare doses,

  • Watching shrimp and algae very closely.

Often, natural tanks don’t need bottled N & P at all.
The plants learn to live on what the system quietly produces.

This is the same spirit as my natural Neocaridina shrimp tank: deep substrate, leaves, and slow, steady water instead of big weekly resets.

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8. Signs You’ve Gone Too Far with N and P

Time to step back if you notice:

• A sudden burst of algae right after you increase N or P.

• Nitrate stays very high every week (for example 40–80 ppm) even with normal feeding.

• Shrimp hide more than usual or seem stressed right after dosing.

• Water looks persistently cloudy without another clear cause.

If this happens:

• Reduce or stop N & P dosing for a while.

• Do one or two moderate water changes (if your style allows it).

• Go back to a simpler plan: a little Fe & K, and let food handle most N & P again.

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9. Final Thoughts

So, do heavily planted shrimp tanks need N and P?

• Many light or medium-planted shrimp tanks do fine with no extra N and P – food and waste are enough.

• Heavily planted, lightly stocked tanks sometimes benefit from a small, careful boost of nitrate and phosphate, especially when tests always show zero and new growth looks tired.

You don’t have to choose one “religion” forever.

You can:

1. Start with no bottled N & P.

2. Watch plants, shrimp, and nitrate readings.

3. Add a little only if the tank clearly asks for it.

As long as you move slowly, stay curious, and keep shrimp in mind, nitrate and phosphate can stay quiet helpers in the background—not the villains of your aquascape.