Guides

• Why pH Rises and Falls Every Day With CO2 Injection

  A daily pH swing with CO2 injection is normal. Water Kiwoogi’s simulator shows a timed solenoid swings pH between 6.67 and 7.62 — and still cycles faster than a 24/7 valve that holds pH low all day.

• Fish You Can Keep Without a Heater

  Some fish live fine with no heater. White cloud minnows and medaka survive 90 days at room temperature, but a heaterless betta dies in just 2 days.

• Why corydoras need a sand substrate

  We ran the Water Kiwoogi simulator with 6 panda corydoras on sand vs. gravel in the same 60 cm tank. All 6 survive 90 days on sand, but on gravel they all die by day 60.

• Why Anubias Rots When You Bury It in Substrate

  Running the Water Kiwoogi simulator: bury an epiphyte like Anubias in substrate with no rock or wood anywhere, and on a short light schedule its rhizome fully rots, knocking the tank out of its settled state. One piece of driftwood stops it.

• Why Seiryu Stone Raises KH

  We ran a 24.3L nano shrimp tank through the Water Kiwoogi simulator. Three seiryu stones push KH to 9.97 by day 60 and wipe out all 10 bee shrimp; even one stone leaves only 3 alive. Inert rock leaves 8 alive.

• Why driftwood turns the water brown and lowers pH

  We ran driftwood setups through the Water Kiwoogi simulator. Two pieces drop pH to 7.27 and three to 7.06, but three pieces leave fewer cardinal tetras alive (7/10) than two (9/10).

• Why Copper-Based Medication Kills Shrimp and Snails

  We dosed copper-based ich medication in the Water Kiwoogi simulator. Shrimp and snails died instantly, while the fish in the same tank stayed fine. Here’s why invertebrates need to come out first.

• Do Otocinclus or Nerite Snails Actually Clean Up Brown Algae?

  A Water Kiwoogi simulator run: nerite snails curb brown algae from day one, but otocinclus added that early can die from their own ammonia within 18 days.

• Why Floating Plants Keep Algae Down

  We ran the Water Kiwoogi simulator on a 60cm tank, changing only the duckweed count. Algae hit 72.2/100 with none but stayed near 0 with 8 duckweed plants.

• Sponge Filter vs Canister Filter: What’s the Real Difference?

  We ran a sponge filter and a canister filter through the Water Kiwoogi simulator. At 10 fish they were identical. At 25 fish, the sponge filter lost all of them while the canister filter kept 15.

• Do You Really Need an Air Pump?

  We ran the simulator with only a low-agitation canister filter. Only the stream-loving panda garra died of low oxygen — a small air pump kept every fish alive.

• Does More Bacteria Starter Mean a Faster Cycle?

  We ran the Water Kiwoogi simulator with different doses of bacteria starter. A 10-fish tank cycled in 3 days with 2 doses (₩44,000) — 20 doses (₩440,000) gave the exact same result, because the colony is capped by surface area.

• How to Pick the Right Heater Wattage

  We ran the Water Kiwoogi simulator with a mismatched heater. A 25W heater in a 170L tank only reached 20.57°C in a 16°C room, killing all 10 neon tetras from day 34, but a 100W heater kept all 10 alive at 24.89°C.

• Why You Should Keep Only One Betta

  We ran a betta with six cherry shrimp for 180 days. The betta stayed healthy; the shrimp died from day 100 — the model still can’t compute two males fighting.

• How Many Schooling Fish Should You Keep Together?

  We simulated neon tetras in groups of 3, 5, 6, and 10 for 90 days. Below the minimum school size of 6, they die even in perfect water; at 6 or more, none do.

• Why Small Tanks Are Actually Harder

  The Water Kiwoogi simulator shows why nano tanks are harder: a betta can’t fit in 6.8 L, and one mistake killed shrimp in 11 days there vs 49 in a bigger tank.

• Goldfish in a Bowl — Why Not

  We ran two goldfish in a 25 cm fishbowl through the Water Kiwoogi simulator. Both died on day one, filter or not, but survived 90 days in a tank that fit them.

• Why New Aquarium Soil Releases Ammonia

  The Water Kiwoogi simulator shows fresh planted-tank soil leaches ammonia and nitrite even with no fish in the tank at all. Here are the numbers by tank size, why waiting alone does not make it safe, and why reused soil cycles fast.

• Which Fish Can Handle Plain Tap Water, and Which Can’t — pH and Hardness

  We ran the Water Kiwoogi simulator on a 60cm tank filled with plain tap water for 90 days. All 10 guppies thrive, but cardinal tetras drop to 4 of 10 because the pH is wrong — mixing in 50% RO water brings survival up to 9.

• Keeping Tropical Fish Without a Heater in Winter

  We ran the Water Kiwoogi simulator with no heater in winter. At a room of 18°C, six neon tetras were wiped out in three days; at 14°C they started dying the same day. Cycling itself slowed down too.

• Why Cryptocoryne Leaves Melt After a Big Water Change

  We ran Cryptocoryne wendtii through the Water Kiwoogi simulator. A water change of 40% or more drops its health from 100 to 72 instantly, taking about two weeks under normal light to recover. Weekly 50% changes never give it that chance.

• What Happens If You Skip the Dechlorinator

  Skipping dechlorinator on every water change keeps knocking back the filter bacteria colony. The Water Kiwoogi simulator shows cycling taking three times longer, and a tank that looked stable needing months longer to truly settle.

• Why Nitrate Keeps Climbing

  Ammonia and nitrite drop to near zero once a tank finishes cycling, but nitrate does not. The Water Kiwoogi simulator shows nitrate climbing past the safety line by day 90 with no water changes, and compares how plants and water changes slow it down.

• What Happens If You Don’t Match the Temperature When You Change the Water

  We ran unmatched water-change temperature through the Water Kiwoogi simulator. A healthy tank was unaffected, but an understocked, already-weakened tank got ich from the swing and was wiped out 18 days sooner.

• Why Shrimp Die Before Fish

  Cherry shrimp die before neon tetras because their nitrite tolerance is much lower. We added both to an uncycled tank in the Water Kiwoogi simulator and ran 30 days to see exactly how many actually die.

• What happens when you overfeed

  Feeding more doesn’t make fish grow faster. We ran a 60cm tank with weekly water changes for 60 days, changing only the feeding rate, to see how much nitrite and nitrate actually move.

• Why You Shouldn’t Add All Your Fish at Once — Staggered Stocking

  Running it through the Water Kiwoogi simulator, dumping 15 fish into a new tank at once kills every one of them. Cutting it to 9 didn’t help — only splitting the batch into three waves let the last group survive.

• Why Fish Gasp at the Surface — Overstocking and Low Oxygen

  We ran the Water Kiwoogi simulator on a tank where fish gasp at the surface — a low-oxygen warning sign. Eight more fish was the difference between life and death, and one air pump fixed it.

• Water Turned Cloudy After Adding Fish — Food and Organic Waste

  Did everything right, even added a bacteria starter, and the water still clouded up after you added fish? The portion size might be the real culprit. We ran the same tank at different feeding rates to see how much it matters.

• Why Fish Die in Clear Water — Ammonia and Nitrite You Can’t See

  Running it through the Water Kiwoogi simulator shows clear-looking water has nothing to do with ammonia or nitrite levels. Two tanks that look equally clear end up with opposite outcomes — one loses all six fish, the other doesn’t.

• Why New Tank Glass Gets Brown Algae (Diatoms) — and When It Clears

  A Water Kiwoogi simulator run shows diatoms feed on silica from new substrate and tap water — and a fishless display tank can stay coated far longer than a stocked, fed one.

• Why New Tank Water Turns Cloudy — and When a Bacterial Bloom Clears

  Running the Water Kiwoogi simulator shows a new tank turning cloudy a few days after setup and clearing on its own within about a week — but clearing up doesn’t mean it’s safe, and the numbers back that up too.

• Why fish die within a week in a new tank

  Run it in the Water Kiwoogi simulator and an uncycled new tank can start killing fish in as little as 6 days, depending on tank size. Here’s why, with the numbers.

• Is a No-Water-Change Tank Possible?

  We ran a 60cm tank for 90 days in the Water Kiwoogi simulator. Heavy planting alone kept nitrate down but let buffering capacity (KH) crash on day 77 just like the unplanted tank — only dosing KH booster to match actual consumption kept the tank stable.

• Fishless Cycling — Using an Ammonia Solution

  We tested dosing an ammonia solution every 3 days versus daily in the Water Kiwoogi simulator. Every-3-days finishes cycling by day 42, but daily dosing leaves nitrite stuck near 54.6ppm even after 90 days.

• Why angelfish and neon tetras should not share a tank

  We ran a 120cm tank with 2 angelfish and 6 neon tetras for 90 days in the Water Kiwoogi simulator. Water quality stays clean the whole time, yet predation kills all 6 neons between day 43 and day 57.

• Why pH Crashes When KH Runs Out

  We ran a 10-neon-tetra tank for 180 days in the Water Kiwoogi simulator. With no water changes, KH drains and pH gets pinned at 5.0 from day 70, wiping out the tank by day 144 — a weekly 25% water change keeps KH up and every fish survives.

• Why algae grows when the light is strong

  We ran the Water Kiwoogi simulator on the same high-light 60cm tank with three plant setups over 60 days. No plants hit an algae index of 72 and an “Algae Hell” ending; adding CO₂ to the same plants brought it down to 0.4.

• How Often Should You Change the Water?

  We ran a 60cm tank for 90 days under three water-change habits in the Water Kiwoogi simulator. Skipping water changes entirely let nitrate cross the safety line and eventually crashed the buffering capacity, while one big monthly change came close to the line each time even though its average was similar.

• How Many Fish for Your Tank Size

  We ran the Water Kiwoogi simulator on 45cm, 60cm and 90cm tanks to see how many neon tetras each one can hold. Keep the same filter and a bigger tank doesn’t scale stocking proportionally, and fast swimmers like zebra danios died even with plenty of volume if the tank wasn’t long enough.

• Why Fish Die at Dawn — Overnight Oxygen

  We ran the Water Kiwoogi simulator on a planted tank where oxygen drops all night, lowest at dawn — only the sensitive fish died. A small air pump fixed it.

• How Long Does Cycling Take — Soil vs. Sand Tanks

  We ran the Water Kiwoogi simulator on a soil substrate and a sand substrate to compare cycling time. The bacteria starter and stocking date mattered more than the substrate itself.

• Why Isn't Nitrite Dropping?

  We ran the Water Kiwoogi simulator on three real causes of stuck nitrite — normal lag behind ammonia, restocking too soon, and skipping dechlorinator — and compared the actual numbers.