75-Gallon High-Tech Iwagumi Aquascape (Intermediate)
A 75-gallon Iwagumi: a few stones, one carpet, and a great deal of deliberate empty water. It is a proper display tank with room to build depth. Pressurised CO2, active soil and real light — faster growth, more colour, and a tank that needs you every week. 1 plant species, Seiryu Stone, and 5 livestock groups checked against each other for compatibility — every quantity below sized to 75 gallons and every plant chosen for an intermediate.
Generate this exact design in the studio →
More than a design — your whole aquarium, handled
Everything below is generated for this 75-gallon Iwagumi build — 1 plant, 5 livestock groups, and gear sized to 75 gallons. The studio does the same for your tank, free.
Hardscape — what to buy and how to place it
Seiryu Stone is blue-grey, sharply angular, cut through with white calcite veins that run the same way on every piece. Seiryu is a carbonate rock, so it slowly raises KH, GH and pH. That suits most community fish and is worth knowing if you are keeping soft-water species — test your KH a fortnight after filling rather than assuming your tap numbers still apply. Keep every stone’s veins running in the same direction; it is the single thing that makes a group read as one broken rock rather than several unrelated ones.
At 75 gallons, plan on five to seven pieces in clearly unequal sizes. An odd count is easier to compose, and one piece should obviously lead — a group of similar-sized pieces spread evenly across the tank is the most common way a first scape goes flat.
Iwagumi is built from named roles, not from a pile. The Oyaishi is the main stone: the largest, set on a third of the tank width rather than the centre, leaning very slightly off vertical. The Fukuishi supports it from the opposite side at roughly two-thirds its size, and the Soeishi is smaller again and sits close to the Oyaishi. Odd numbers only, and no two stones the same size.
Substrate
Aqua soil (e.g. ADA Amazonia / UNS Controsoil), built to about 3–4" and sloped higher at the back. Active soil buffers soft, slightly acidic water and feeds roots. Slope higher at the back for depth.
Fresh aqua soil leaches ammonia for the first one to three weeks. That is normal and it is also why you do not stock a high-tech tank early: run it, change a good volume of water two or three times in that first fortnight, and wait for ammonia and nitrite to read zero before any livestock goes in.
The whole floor of this tank is Staurogyne sp. 'Porto Velho', so the substrate contour IS the layout — there is no background planting to hide a flat bed. Build a real slope from front to back and let the carpet run up and over it; that rise is what gives an otherwise open tank its depth. Plant in small clumps a couple of centimetres apart and let them spread sideways to meet, rather than packing them in to look finished on day one.
At 75 gallons the substrate is a real purchase, not an afterthought — budget for it early and buy it all at once, because a bed topped up later with a different bag rarely matches.
Plant list & placement
Plant back to front, into damp substrate with the tank only part-filled — it is far easier than fighting buoyancy in a full tank. Staurogyne sp. 'Porto Velho' is the tallest thing in this plan at around 3", so it sets your back row and everything else steps down in front of it.
Nothing in this plan grows quickly, which is the point — it means very little trimming, but it also means the tank takes longer to look established and gives algae a wider opening in the first two months. Keep the light modest until the plants are visibly growing.
Stocking
This stocking is built to spread through the tank rather than crowd one layer: Cardinal Tetra and Congo Tetra share the open middle water and Sparkling Gourami and Pygmy Cory share every level. A tank where every fish occupies the same band looks half-empty even when it is fully stocked, and the fish themselves compete more.
Keep Cardinal Tetra in 6 or more, Pygmy Cory in 8 or more and Congo Tetra in 6 or more. These are not decorative numbers — a shoaling fish kept in threes spends its life stressed, colours down and hides, and people then conclude the species is dull. The counts in the list above are already scaled to this tank.
Sparkling Gourami is the centrepiece. Tiny characterful labyrinth fish that croaks; loves planted cover.
Olive Nerite Snail is the clean-up crew, and in a planted tank it earns its place — grazing biofilm and soft algae off the hardscape and leaves faster than you can. Add it last, once the tank has some algae to eat, and drip-acclimatise rather than dumping the bag in.
- Cardinal Tetra — Keep Cardinal Tetra in a group of at least 6 — kept in ones or twos they get stressed, shy, and nippy.
- Sparkling Gourami — Keep Sparkling Gourami in a group of at least 3 — kept in ones or twos they get stressed, shy, and nippy.
- Pygmy Cory — Keep Pygmy Cory in a group of at least 8 — kept in ones or twos they get stressed, shy, and nippy.
- Congo Tetra — Keep Congo Tetra in a group of at least 6 — kept in ones or twos they get stressed, shy, and nippy.
The largest fish here is roughly 3.0× the length of the smallest, which is the point at which size alone starts to matter — that gap was checked against mouth size and feeding behaviour, not just temperament. Every pairing was run through Skapelab’s compatibility engine and anything returning even a caution was swapped out rather than published. Check any substitution you make there before you buy.
Equipment
| Category | Recommendation | Notes |
|---|---|---|
| Filtration | Fluval 307 Canister Filter | ~$155–200 |
| Lighting | Finnex Planted+ 24/7 HLC 48" | ~$98–135 |
| Co2 | CO2Art Pro SE Series Regulator + 5lb Cylinder | ~$145–185 |
| Heating | Inkbird IBS-M1 Smart Heater | ~$48–65 |
| Substrate | Tropica Aquarium Soil 9L | ~$42–58 |
| Fertilizer | Estimative Index DIY NPK Dry Ferts Kit | ~$28–45 |
| Testkit | API Freshwater Master Test Kit | ~$28–42 |
| Water treatment | Seachem Prime 500ml | ~$12–20 |
| Bacteria | Seachem Stability 250ml | ~$8–14 |
What the first two months look like
| Week 1 | Hardscape in, planted, filled and running with no livestock. CO2 comes on an hour before the lights and off an hour before they go out; aim the drop checker at a green, never yellow. Keep the photoperiod short, around six hours, while the plants root. |
| Weeks 2–4 | Cycling, and the ugly phase. Brown diatom dust on the glass and hardscape is normal in a new tank and passes on its own once silicates are used up; the fresh soil is also still releasing ammonia, so keep changing water. Some plants will melt back and regrow in their submersed form — that is conversion, not death, so trim the mush and leave the roots. Do not stock until ammonia and nitrite both read zero. |
| Weeks 4–6 | Stocking begins, a few animals at a time with a fortnight and a water test between additions. The carpet should be visibly running now; resist raising the light to hurry it. |
| Months 2–3 | The scape fills in and the routine settles into the schedule below. Judge the design now rather than on day one; a planted tank is not finished until it has grown into itself. |
Care schedule
| Daily | Feed lightly — as much as they clear in a minute or two — and take ten seconds to count heads and look at the plants. Check the drop checker is green before the lights come on. |
| Weekly | 40% water change — about 30 gallons on this tank — using a tap-fed water changer — at this volume buckets stop being realistic. Dose your macros and micros after the change, not before. Wipe the glass and check the CO2 cylinder pressure. |
| Monthly | Rinse filter media in old tank water — never under the tap, which kills the bacteria colony you spent six weeks growing. Test KH, GH, pH and nitrate. Check for anything the weekly routine keeps missing behind the hardscape. |
| Every few months | Replace the CO2 diffuser membrane, check the regulator has not crept, and pull the deepest stems for a hard replant. Lights lose output long before they fail — plan on replacing LEDs or bulbs on a schedule, not on symptoms. |
Make it yours
This is a starting point. Open it in the studio to swap plants, resize to your tank, and get a hand-illustrated render, placement diagram, and shopping list — free.
Start this build →