Iwagumi aquascapes are hugely popular, anchored by aesthetic rocks in carpets of rolling hills. But 2 common challenges remain:

• How to have clean algae-free rocks?
• How to have a thriving, algae-free carpet?

With the right parameters, Iwagumi aquascapes are surprisingly easy to maintain.

Here are the 3 Steps, the 2Hr Way:

Step 1: 50 PAR

To maintain algae-free rocks, adjust lighting to 40~50 umols of PAR (measured at substrate level).

Precision matters here: 66 PAR is not visually different from 50 PAR, but 30% more energy = green rocks.

Note the green algae on the Seiryu rocks at the top right above. Incidental light from an adjacent tank increased light strength at that zone to 66 umols of PAR, enough for persistent algae to grow.

Refer to this earlier post on how to use an iphone App to estimate PAR.

Contrary to the popular belief that carpets require very strong lighting, even ~30 PAR is sufficient for popular carpeting plants: Eleocharis acicularis, Eleocharis parvula, Hemianthus callitrichoides 'Cuba', Utricularia gramminifolia, Micranthemum tweediei 'Monte carlo' etc.

STEP 2: zero N

In our Iwagumi aquascapes, nitrates in the water (NO3) measure an average of Zero. We use APT1 (comprehensive nutrition without nitrates and phosphates) to consciously keep N & P levels close to zero. This helps to keep glass and rocks clear of Green Dust and other algae.

How does this work? We nourish the carpet through rich aquasoil (APT START for new tanks, APT JAZZ after 3 months). This combination of lean water + rich substrate is a key strategy.

Nitrates measure zero because of plant absorption, which takes place continually. It is not necessary to have a positive residual reading to grow plants well. So when we measure NO3 at the end of day, it reads zero.

Step 3:Vacuum Cleaning

Accumulated detritus (note the 'brown dust' above on the rocks) invites algae. Iwagumi aquascapes are especially susceptible due to overall lower plant mass (space taken up by sandbanks, or hardscape). This makes cleanliness especially important.

We perform 50%-80% water changes on a weekly (or fortnightly basis), taking care to remove accumulated detritus on rocks and on the substrate surface.

The humble pipette does a good job of gently stirring up detritus, which we siphon away. For larger tanks, a turkey baster or equivalent can be used instead.

What else?

Spot-dripping APT FIXLITE or APT FIX on hardscape during water change is highly effective in making them sparkling white.

1. Drain the tank to expose rocks.
2. Spot-drip on targeted areas.
3. (optional) Use a paintbrush to cover larger surfaces.
4. If you exceed 1ml per 10L of tank volume, fill the tank and perform another 50% water change.
5. All carpets become overgrown after some time. This is how we maintain them.