Reef Octopus Regal 300SSS 12in Space-Saving Protein Skimmer (VarioS) fit check
Reef Octopus Regal 300SSS 12in Space-Saving Protein Skimmer (VarioS) is an in-sump space-saving with controller protein skimmer rated up to 400 gallons. Box ratings assume light stocking, so ReefCrafter scales them by bioload: about 265 gallons lightly stocked, 200 gallons medium, or 160 gallons for a heavily fed fish tank.
Reef Octopus Regal 300SSS 12in Space-Saving Protein Skimmer (VarioS): fits roughly 200-400 gallon systems. Specs, compatibility math, sizing risks, and…

Who it is for
Good fit for
- ✓ 200-400 gallon systems, per the catalog fit range.
- ✓ Heavily fed tanks up to about 160 gallons, or lightly stocked tanks up to about 265 gallons.
Not a fit for
- ✕ Tanks under about 200 gallons; it is sized above them.
- ✕ Systems over about 400 gallons without adding capacity elsewhere.
- ✕ Heavy-bioload tanks above about 160 gallons; the box rating assumes light stocking.
- ✕ Hang-on-back or AIO setups without a sump chamber deep enough for it.
Listed features
- 12 in body
- in-sump
- space-saving footprint
- controllable VarioS DC pump
Compatibility math
Bioload headroom
Example: On a 75g mixed reef, ReefCrafter wants about 150g of skimmer rating for medium bioload.
Reef Octopus Regal 300SSS 12in Space-Saving Protein Skimmer (VarioS) is rated around 400g, so the useful question is whether that clears the fish load with margin.
Risk notes
- A skimmer can be fine for a light reef and thin for the same tank once feeding and fish load increase.
Professional fit context
- Compare rated maximum gallons, physical fit, cup clearance, noise, and bioload margin.
- Reef Octopus Regal 300SSS 12in Space-Saving Protein Skimmer (VarioS) fits roughly 200-400 gallon systems; confirm that range against the final display volume, sump volume, and livestock plan.
Alternatives to compare
- Royal Exclusiv Bubble King Double Cone 250 Protein Skimmer
Same 400 gallon rating; compare format and features instead.
- Nyos Quantum 220 Protein Skimmer
500 gallon rating vs 400: more skimming headroom.
- Royal Exclusiv Bubble King Supermarin 200 Internal Protein Skimmer
500 gallon rating vs 400: more skimming headroom.
Livestock this affects
- Powder blue tang
Bioload score 3.4; size the skimmer for heavy feeding.
- Foxface rabbitfish
Bioload score 3.2; size the skimmer for heavy feeding.
- Purple tang
Bioload score 3; size the skimmer for heavy feeding.
- Yellow tang
Bioload score 3; size the skimmer for heavy feeding.
Full spec snapshot
- Category
- Skimmers
- Build tier
- Premium
- Estimated price
- $899
- Tank fit range
- fits roughly 200-400 gallon systems
- Format
- In Sump Space Saving With Controller
- Rated skimmer capacity
- 400 gal
Related reading
Questions
Is the Reef Octopus Regal 300SSS 12in Space-Saving Protein Skimmer (VarioS) big enough for my tank?
It is rated up to 400 gallons. ReefCrafter wants 1.5x, 2x, or 2.5x the display volume in skimmer rating by bioload, so it fits about 265 gallons lightly stocked, 200 medium, or 160 heavily fed.
What tank size is the Reef Octopus Regal 300SSS 12in Space-Saving Protein Skimmer (VarioS) for?
ReefCrafter's catalog fit range for it is 200-400 gallon systems. Confirm that against your final display volume, sump volume, and livestock plan rather than the box label alone.
What should I compare the Reef Octopus Regal 300SSS 12in Space-Saving Protein Skimmer (VarioS) against?
Royal Exclusiv Bubble King Double Cone 250 Protein Skimmer (Same 400 gallon rating; compare format and features instead); Nyos Quantum 220 Protein Skimmer (500 gallon rating vs 400: more skimming headroom); Royal Exclusiv Bubble King Supermarin 200 Internal Protein Skimmer (500 gallon rating vs 400: more skimming headroom).
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