Corrections
Every change we make to a published page is logged here, with the date and what changed. If you spot an error we haven't fixed, email corrections@reefcalcs.com.
Errata
26 entries, newest first.
- Factual
Candy cane and chalice coral sheets re-sourced from taxonomic papers, coral farms and reef-hobby publications instead of mainly retailer pages. Candy cane: the 'trumpet' sold as Caulastrea curvata was moved to the genus Astraeosmilia in 2021, so the light note about it no longer applies; flow is now low to moderate, following a coral farm that prefers low flow, the PAR range is given with its sources, and a branch-fragging method replaces 'no method found'. Chalice: Echinophyllia sweeper tentacles have been seen over a foot long, and it can digest neighbouring corals with filaments at night; light advice is now given as a range rather than 'low to moderate'; Mycedium has no tentacles and feeds through mucus, and growth-rate claims conflict between sources. Lifespans added where a source exists (skunk cleaner shrimp, royal gramma, blue hippo tang); the yellow tang notes the only aquarium figure found and why it's weak, and the kole tang page gives other surgeonfishes' ages as context only; and the giant danio's size now comes from FishBase's figure for the trade species.
- Factual
Fish and invertebrate care sheets rewritten against their sources, with every claim cited (yellow, kole and blue hippo tangs, ocellaris clownfish, royal gramma, six-line wrasse, yellow watchman goby, lawnmower blenny, skunk cleaner shrimp, tuxedo urchin, nassarius snails, and the leather coral sheet). Errors fixed: the yellow tang page said fish go without daily greens develop HLLE and that it hybridizes with other Zebrasoma; neither is supported, and HLLE's cause is unresolved. Its minimum is now 100 gallons (LiveAquaria) instead of 75. The kole tang was listed as 5 inches and peaceful with other tangs; it reaches about 7 inches and is aggressive toward other tangs, with a 75 gallon minimum. The six-line wrasse was credited with eating pyramid snails and bristleworms; only its predation on adult Acropora-eating flatworms is shown in a study, and it didn't eat their eggs. The cleaner shrimp page said it reduces ich; no study has tested that. The royal gramma was said to never bother tankmates and to be widely available captive-bred; it fights its own kind and other basslets, and captive-bred fish are only occasionally available. The lawnmower blenny is mainly a detritus eater, not a reliable algae cure, and its minimum is now 40 gallons (Reef Builders). Unsupported figures such as '1–2 nassarius per 10 gallons' and the blue tang's growth timeline were removed.
- Factual
Freshwater species data checked against Seriously Fish profiles; minimum tanks are now the smallest standard tank that meets Seriously Fish's recommended base, including its depth, and its height where it gives one. Angelfish: 55 → 75 gallons (100 × 40 × 50 cm, so neither the 13-inch-deep 55 nor the 16-inch-tall 60 breeder qualifies). Rummy-nose tetra: group 6 → 10 and a 36-inch tank; its name is now Petitella rhodostoma. Silver dollar: 75 → 125 gallons (180 × 38 cm for an adult group). Clown loach: 150 → 180 gallons (180 × 60 cm). Common pleco: 150 → 125 gallons (ScotCat's 6-foot tank). Swordtail: 30 → 33 gallons, 48 in long. Bolivian ram: single fish or bonded pair, on a 90 × 45 cm base. Discus stays at 75 gallons, but the page now says Seriously Fish's 120 × 45 × 45 cm figure is for juveniles or a pair. Several minimums fell where Seriously Fish's base is smaller than our earlier figure: bristlenose pleco 30 → 15, cockatoo dwarf cichlid 25 → 15, German blue ram and otocinclus 20 → 15, convict 40 → 30, firemouth 55 → 33, electric yellow 55 → 30 (36 × 18 in). Temperature, pH and hardness ranges now follow the cited profiles. Ocellaris clownfish and blue tang sizes corrected to 4 and 12 inches. Unsourced care notes were removed (an apistogramma sex ratio, a discus water-change figure, 'EI' ram strains, a pleco growth rate). Added Boeseman's and dwarf neon rainbowfish, lemon, serpae and odessa tetras and barbs, rosy barb, kribensis and giant danio.
- Clarity
20 gallon stocking page: the two plans with a single honey gourami now use a pair, because Seriously Fish suggests a pair or small group (its notes say 4–6). With a pair, the harlequin rasbora plan uses the whole bio-load budget, and the page now says so instead of claiming room to spare.
- Factual
Coral care sheets rewritten against their sources, with every claim cited (torch, frogspawn, hammer, zoanthids, mushrooms, Acropora, Montipora, Goniopora). Errors fixed: the hammer page said hammers can touch torches 'from the same parent colony' and the frogspawn page warned against hammers 'from a different parent colony'. In fact frogspawn and hammer usually tolerate contact and torches should touch neither, whatever colony they came from. The torch page called polyp bailout 'Anthelia-style' splitting; bailout is a stress response, not propagation. The mushroom page named Rhodactis as the fish-eating elephant ear; that is Amplexidiscus fenestrafer. The zoanthid page said palytoxin is a Palythoa problem; it has also been found in some Zoanthus, and the page now carries CDC's handling precautions. Bristleworm infestation was removed as a cause of death because no source supports it, the Goniopora spacing is now 3–4 inches (Reef Builders) rather than 6, and frogspawn and hammer are listed under Fimbriaphyllia, the genus WoRMS now uses. Minimum tank sizes we couldn't source were replaced with sizing guidance.
- Factual
Freshwater species data, checked against Seriously Fish species profiles. These figures drive the stocking calculator and the tank size pages. Neon tetra: minimum tank 10 → 15 gallons, group 6 → 8. Zebra danio and GloFish: 20 → 30 gallons (36 in long), group 8. Endler's livebearer: 5 → 10 gallons. Cardinal tetra: adult size 2 → 1.5 in, group 6 → 8. Corydoras: 2.5 → 3 in. Minimum groups are now 8 for harlequin rasboras, 10 for celestial pearl danios and 12 for black skirt tetras. Several temperature ranges were narrowed, among them kuhli loach (73–86 → 72–79 °F) and mystery snail (68–82 → 70–78 °F). Kuhli loach and mystery snail scientific names now match what is usually sold: Pangio semicincta (sold as P. kuhlii) and Pomacea diffusa.
- Factual
All-For-Reef calculator: removed a dosing rule of thumb ('1 mL per 25 L per dKH') that Tropic Marin does not publish. The page now follows Tropic Marin's schedule: start at 5 mL per 100 L per day, raise by 2.5 mL per 100 L each week until alkalinity holds at 7–9 dKH, and don't exceed 25 mL per 100 L per day.
- Factual
Red Sea Foundation B strength: the Red Sea Foundation and alkalinity dosing calculators used 0.034 dKH per mL per 100 L. Red Sea's figure is 0.036 meq/L, which is 0.1 dKH, so Foundation B doses were about 2.9 times too high (a 100 gallon tank needs about 38 mL per dKH, not 111 mL). The Foundation page also said Red Sea's daily calcium limit is 50 ppm; it is 20 ppm, alongside 1.4 dKH alkalinity and 10 ppm magnesium. Its targets now follow Red Sea's table by tank type.
- Clarity
Tank size pages: the freshwater filled weight now assumes a 1 inch gravel bed sized to the tank's footprint instead of a flat 20 lb, which overstated small tanks (a 2.5 gallon read 48 lb filled; it is about 32 lb). Larger tanks read a little heavier, for example a 75 gallon at about 779 lb instead of 749 lb.
- Factual
Apex vs HYDROS comparison: the page recommended the HYDROS Control 4, which CoralVue has discontinued. It now compares the Apex A3 with the HYDROS Launch, its current entry controller, using what each manufacturer's product page says is in the box. The warranty and open-API rows were removed because the current HYDROS pages don't state them, and the A3's included probes now match Neptune's listing (temperature and pH; ORP and salinity are Apex Pro only).
- Factual
Vinegar vs vodka carbon content: the vinegar dosing guide said 5% vinegar carries 0.05 g of carbon per mL and that vodka carries roughly 3 times as much. 0.05 g is the acetic acid; the carbon is 0.02 g per mL, so 80-proof vodka (about 0.16 g of carbon per mL) carries roughly 8 times as much. The page now also has a vinegar and vodka dosing calculator built on the corrected figures.
- Factual
Calcium chloride pack sizing: the calcium dosing page sized the bulk calcium chloride pack as if it were dihydrate (about 225 g a month for the example tank), but the linked 7 lb bucket is anhydrous, which is about 25 % stronger by weight. The example now uses about 169 g a month, the product is labelled anhydrous, and its notes give the anhydrous Recipe #1 weight (about 377 g per gallon instead of 500 g).
- Link
Product links: every Amazon listing on the site was re-checked. Eight had become unavailable and were replaced or removed, 41 products that only linked to an Amazon search now link to the specific listing, and gear Amazon doesn't stock (BRS Pharma two-part, EcoTech Radion, VorTech and Vectra, the Hanna HI772, Apex A3) now links to a store that does. Hand-typed prices were removed from product blocks, because they went out of date.
- Factual
Two-part alkalinity yield: the two-part guide and the methodology page said 1 mL of Recipe #1 alk stock per gallon raises alkalinity 0.135 dKH. The correct figure is about 1.41 dKH, so the guide's worked example (741 mL/day for 100 gal losing 1 dKH) overstated the dose roughly tenfold; it is now about 71 mL. The alkalinity dosing calculator already used the correct value. The alkalinity and calcium calculator FAQs, which also overstated the dose, are fixed too.
- Factual
Kalkwasser strength: saturated kalk carries about 40 meq/L (~112 dKH) of alkalinity alongside ~800 ppm Ca. The kalk-drip calculator used 40 dKH and under-reported alkalinity added by about 2.8×; the kalkwasser page text said 2 meq/L. Both calculators now share the same constants and agree (1 % of tank volume per day ≈ +1.1 dKH, +8 ppm Ca).
- Factual
Magnesium recipe: the site described two different DIY blends with three different dose yields. Everything now uses Holmes-Farley's Recipe #3 (7¼ cups MgCl₂·6H₂O + ¾ cup Epsom salt in 1 gal of water, ≈40,000 ppm Mg; 1 mL/gal ≈ +10.6 ppm). The calculator previously assumed a 47,000 ppm stock, so its doses were about 18 % low. This supersedes the 2026-05-25 entry below.
- Factual
Underwater PAR: the lighting guide told Apogee MQ-510 owners to multiply readings by 1.25. Per Apogee, the MQ-510 applies its immersion correction in firmware, so its readings are used as-is; the SQ-500 head needs ×1.32 and the SQ-110/120 (MQ-200) ×1.08 (previously listed as 1.32). Coral PAR bands are now the same on every page.
- Factual
Calcium consumed per dKH of alkalinity is 7.15 ppm. The calcium parameter page said 5–6 ppm and the two-part imbalance calculator used 7.5.
- Factual
Product mix-ups: four LED fixture pages linked a different light than the one reviewed; the nitrate page and nitrate troubleshooting linked an alkalinity test kit; BRS Pharma soda ash was labelled as sodium bicarbonate; and the Randy vs BRS comparison called baked baking soda pH-neutral (baked baking soda is soda ash and raises pH like any carbonate; the pH-mild option is unbaked bicarbonate). Single-sensor ATOs are no longer recommended where the site says a two-sensor failsafe is required.
- Factual
Privacy policy and About page: the privacy policy said Google Analytics was not in use and that analytics consent defaults to denied. GA4 is in use; analytics now defaults to denied for EEA/UK/Swiss visitors and granted elsewhere, and the policy says so. The About page said affiliate links never appear near calculator results; they appear in a labelled block below the result.
- Clarity
Methodology page: the heater-sizing, substrate-density and live-rock descriptions now match what the calculators actually compute, and the claim that every deploy runs the test suite was removed (tests run before each change is pushed).
- Link
Fixed three broken internal links to /guides/vinegar-carbon-dosing, /guides/icp-testing-for-reef-tanks, and /calculators/aquarium-sand after those pages were renamed. Updated every reference across the site.
- SEO
Added descriptive og:image:alt text to 4,636 pages so the social-share image is announced to screen readers and link-preview crawlers.
- SEO
Tightened meta titles and descriptions across the site so they render fully in search results instead of being truncated mid-phrase.
- Clarity
Reworded the inch-per-gallon stocking guidance to state plainly, up front, that it is a rough starting heuristic for fish only — not a rule for corals or for sensitive species — because it was being read as more precise than it is.
- Factual
Corrected the magnesium dosing reference: the Recipe 3A magnesium chloride / magnesium sulfate ratio now matches Holmes-Farley's published figures. The earlier version overstated the sulfate share, which would have nudged the magnesium result slightly high.
Last reviewed