The Dutch 90P
Twenty species of stem plant in a Dutch street scape, on fresh aquasoil, with CO₂ injected through an inline diffuser. Temperature, pH and conductivity are logged continuously and published straight from the tank; PAR is measured by hand at each plant. The figures below are the recorded values, not a summary of them.
What has actually been recorded
Every figure below is a count taken from the database at page load, not a number typed into the page. Each one links to where the underlying data can be seen.
Why this project exists
This is my 90P Dutch tank, currently on its fourth rescape. I document it with measurements rather than impressions. PAR, water chemistry, plant development, equipment changes and operating conditions are tracked over time to better understand what produces healthy growth and strong coloration. The reasoning behind that approach is set out in the measurement philosophy.
The goal is to create a useful, transparent record of the tank’s development and eventually publish a controlled comparison between the original ADA Solar RGB and the Solar RGB II.
What's planted
Every species in the tank, with the PAR measured at that plant. Values update as new readings are logged.
Four weeks in
Fresh ADA Amazonia leaches ammonia for the first few weeks, so a new scape is run on heavy water changes until it stops. Here is that curve, measured rather than assumed, and the tank growing in underneath it.
Hand-tested with a Seachem ammonia alert and a liquid kit. Once this sits at zero across consecutive tests, the water-change schedule can taper off the every-other-day startup cadence.
How PAR was measured
- Meter
- Apogee MQ-510 underwater quantum meter
- Measurement type
- Underwater PPFD measurements
- Fixture
- Original ADA Solar RGB at 100% output, ADA Shade fitted
- Tank format
- 90P
- Measurement locations
- Twenty repeatable positions corresponding to plant groups
- Sensor position
- Held level at the measured plant or substrate location
- Conditions
- Aquarium light on, room lighting minimized, water clear
- Purpose
- Evaluate usable light distribution across the planted layout
PAR values represent the measured light at each recorded location. They are not universal plant requirements and should be interpreted alongside CO₂, nutrients, plant health, spectrum and canopy height.
PAR distribution by plant
20 underwater measurements were recorded at the planted locations shown above. The table compares the measured PPFD at each position with a practical working range used to evaluate whether light may be limiting growth or coloration. A single number under the middle of a fixture says nothing about what the plant in the corner is getting. Measured mid-photoperiod with an Apogee MQ-510 held level at the plant · August 2, 2026.
Dimmest to brightest
| working range | ||||
|---|---|---|---|---|
| 09Pogostemon stellatus | 50 | 70–110 | not recorded | Lower than working range-20 |
| 10Hygrophila 'Kompakt' | 56 | 40–70 | not recorded | Within working range |
| 04Myriophyllum 'Guyana' | 70 | 40–70 | not recorded | Within working range |
| 05Myriophyllum mattogrossense 'Golden' | 70 | 60–100 | not recorded | Within working range |
| 15Alternanthera 'Super Magenta' | 76 | 70–110 | not recorded | Within working range |
| 19Rotala wallichii | 77 | 80–120 | not recorded | Lower than working range-3 |
| 11Ludwigia arcuata | 80 | 60–100 | not recorded | Within working range |
| 02Lobelia cardinalis 'Mini' | 90 | 50–90 | not recorded | Within working range |
| 12Hygrophila pinnatifida | 90 | 70–110 | not recorded | Within working range |
| 17Rotala macrandra (FULL) | 95 | 100–150 | not recorded | Lower than working range-5 |
| 18Ludwigia 'Pantanal' | 95 | 90–130 | not recorded | Within working range |
| 03Alternanthera reineckii 'Mini' | 100 | 70–110 | not recorded | Within working range |
| 16Ludwigia glandulosa (Peruensis) | 102 | 100–150 | not recorded | Within working range |
| 13Staurogyne repens | 105 | 25–50 | not recorded | Above working range+55 |
| 14Micranthemum 'Monte Carlo' | 122 | 50–90 | not recorded | Above working range+32 |
| 20Rotala macrandra 'Mini' | 125 | 90–130 | not recorded | Within working range |
| 06Rotala 'Orange Juice' | 135 | 70–110 | not recorded | Above working range+25 |
| 08Limnophila hippuridoides | 145 | 70–110 | not recorded | Above working range+35 |
| 07Rotala 'Blood Red' | 155 | 80–120 | not recorded | Above working range+35 |
| 01Vallisneria nana | 176 | 30–50 | not recorded | Above working range+126 |
Working ranges are practical reference ranges compiled from grower guidance and aquascaping experience. They are not fixed biological thresholds. Four are drawn from published figures (Staurogyne repens, Micranthemum 'Monte Carlo', Ludwigia glandulosa, Rotala macrandra); the rest are placed by each plant's established light-demand tier, since no source publishes a hard number per cultivar. Light is one input among several: CO₂, nutrients, spectrum and canopy height all bear on color too.
Lighting
Current fixtureCurrent
Original ADA Solar RGB
- Purchased from Aqua Forest Aquarium approximately six years ago
- Mounted over a 90P format aquarium
- Operated at full output
- Current PAR distribution documented with an Apogee MQ-510
Planned comparisonPlanned
ADA Solar RGB II
The measured constraint on this tank is coverage rather than peak output. The lever for coverage is mounting height, and raising the current fixture made the ends worse because it has no output to spare. The second-generation fixture is stated to be about 1.5 times brighter, and that surplus is what would pay for hanging it higher. Whether it nets out better at the edges of a 90 cm tank is an open question: no PAR distribution figures for it appear to have been published anywhere.
The recorded prediction is that the extra output will buy enough height to leave the ends better off than they are today. It is on record so it can be shown to be wrong. The comparison uses the same aquarium, meter, measurement positions and procedure for both fixtures, at a matched height and again at each fixture’s own best height, and the result will be published whichever way it goes.
- Twenty point PAR map
- Center to edge distribution
- Substrate and canopy measurements
- DLI comparison
- Fixture height comparison
- Photographs using matched camera settings
- Written findings and methodology
Experiments
What the tank is doing right now
CO₂ goes in through an inline diffuser, held under pH control: a Raspberry Pi captures the degassed pH each morning and holds a target drop off that baseline through the photoperiod. This project uses pH drop as an operational control signal rather than an absolute dissolved CO₂ measurement. At near-zero KH the pH/KH table does not apply, so no ppm figure is published here.
Dissolved solids climb as the tank consumes and evaporates, then drop sharply at each water change. Every sawtooth in this trace is a ~53% change. Tracking the creep is what sets the change schedule, rather than a fixed calendar.
Water chemistry · hand-tested with liquid kits
- KH
- 0 dKH · 32d ago
- GH
- 6 dGH · 25d ago
- TDS
- 103 ppm · 41d ago
- Ammonia
- 0 ppm · 4d ago
RODI remineralized with a GH-only booster, so all hardness is deliberate. Near-zero KH is the intended state on fresh aquasoil, not a fault.
What runs it
CO₂ under pH control
A Raspberry Pi reads the degassed pH each morning and holds a target drop through the photoperiod. The hard limits, a pH floor and a time window and a leak sensor, live on the controller, so a stuck script cannot over-gas the tank.
Continuous sensing
Temperature, pH, conductivity, power draw and every outlet state are polled around the clock. Nothing here is typed in by hand.
Light, quantified
PAR is logged per plant against a working range for that species, so “is the light enough” is answered per position rather than guessed about the fixture.
The tank watches itself
A camera captures a frame every hour the light is on, and a vision model reviews one a few times a day for algae and plant health, alerting only when something needs attention.
Setup
Aquarium
- Format
- 90P · 90 × 45 × 45 cm rimless
- Estimated operating water volume
- Approximately 142 L (~37.5 US gal) after substrate, equipment displacement and headspace
Lighting
- Fixture
- ADA Solar RGB
- Shade
- ADA Shade fitted
- Mounting height
- 12″ (about 30 cm) above the water
- Output
- 100%
- Photoperiod
- 9:30am – 4:30pm
Filtration and flow
- Canister
- EHEIM Professionel 5e 700
- Second filter
- ADA Super Jet ES-600
- Surface skimmer
- ADA Vuppa II
- Flow
- Scheduled day / night profile
CO₂
- Target
- Held as a pH drop off the morning degassed baseline
Substrate
- Base
- Power Sand
Fertilization
- Ferts
- 2Hr Aquarist APT
Water
- Source
- RODI · SpectraPure membrane + Pentek prefilters + SpectraPure DI
- Remineralized
- GH booster · KH 0–1 · GH 6
- Top-off
- Automatic (ATO)
Monitoring
- Controller
- Neptune Apex
- pH probe
- Milwaukee MA911B/2
- Conductivity
- Atlas Scientific EZO K0.1
- Automation
- Raspberry Pi running Pearl
Livestock
- Shrimp
- Amano shrimp
- Fish
- None at present, the scape is still growing in
Product names match the live inventory that runs this tank. Linked items have a documentation page covering why they were chosen and what has been observed using them.
Measured and logged with Pearl, a self-hosted dashboard that monitors and runs this tank. Live figures updated Aug 5, 1:54 PM CT.