Dolphin Sigma review

This is a source-based assessment of the U.S. Dolphin Sigma, Product No. 99991036-SPLI, not a hands-on test. Maytronics' exact U.S. page identifies it as an in-ground, corded cleaner and lists floor, wall and waterline coverage for pools up to 50 ft. The same page names Wi-Fi and MyDolphin Plus, a 2.5-hour default cycle, a weekly timer and an additional Ultra-Fine Filter Kit in the box. Those are catalog claims to verify against the exact offer, not a promise that a particular pool or installation will work.

A useful coverage screen, not a fit guarantee

The Sigma's published coverage is broader than a floor-only or floor-and-wall listing: the product table names floor, walls and waterline. It also restricts the stated pool classification to in-ground and lists rectangular, round, free-shape and kidney pools. These fields can narrow a first comparison, but they do not explain how the cleaner handles a particular shelf, step, slope, corner, surface finish or waterline transition. A broad label should not be treated as a result for every geometry.

Maytronics gives the Sigma a maximum pool length of 50 ft. That is a rating for pool length, not a cable measurement. The product image linked from the exact Sigma page shows a cable attached to the marked machine, which supports its corded arrangement; neither that image nor the technical table states cable reach or where a power supply may safely stand. The exact-number manual selector linked from the page returned “No products were found matching your selection.” Without a model-matched instruction document, I cannot confirm the Sigma's operating depth, step or ledge limits, surface restrictions, cord routing, electrical setup, retrieval or care instructions. Ask for current Sigma-specific documentation before relying on it in an unusual pool or installation.

App and schedule claims need careful reading

The exact page names Wi-Fi connectivity and the MyDolphin Plus app. This is enough to treat app availability as documented for the listed configuration, but the page does not enumerate Sigma-specific app actions. It also states “Remote Control: No.” Elsewhere the table says “Automation Mode: Yes,” but does not define what that field means. The app name and automation label therefore do not establish live steering, underwater communication, or a specific remote-control workflow.

The table gives a default cycle time of 2.5 hours and says a weekly timer is available; it marks the delay feature “No.” These are useful routine details when comparing product pages, not independent measurements of cleaning performance or proof that each timed cycle reaches every claimed surface. The page provides no alternative cycle durations. Confirm the exact timer behavior in applicable current instructions rather than assuming the weekly schedule means the robot can be directed from anywhere.

Separate the main filter from the extra kit

Maytronics' technical table calls the main filter a Fine Filter Kit, lists top access, and separately identifies an additional Ultra-Fine Filter Kit in the box. This is stronger package evidence than a filter accessory tile: the extra kit appears in the product's own “Additional Filter in the Box” field. The page does not publish a particle-size grade, and it says the full-filter indicator is “No.” Those omissions matter if your priority is a stated micron threshold or an alert when the basket needs attention.

There is a wording mismatch worth preserving. The product feature copy describes an “extra-large, multi-layer filtration basket,” while the technical table labels the filter type “Fine Filter Kit.” The same page's technical fields list “Active Brush: No,” despite the separate feature phrase “Powerful Active Scrubbing.” I would not turn either promotional phrase into a particle-performance or active-brush claim when the specification table disagrees or is less precise. The included Ultra-Fine kit is documented; its exact particle grade and Sigma-specific cleaning instructions are not.

Handling, included equipment and separate add-ons

The manufacturer lists the robot at 24.63 lb, with net dimensions of 16.732 × 16.043 × 10.299 inches and package dimensions of 23.1 × 19.1 × 13.8 inches. These are published specifications, not measurements made for this assessment. The page does not explicitly state whether a caddy or stand is in the Sigma carton. A product image shows a transport-frame-like structure, but a promotional photograph is not a reliable package list.

The Sigma page's Add-On Accessories section links to a Premium Caddy Cover (9991795-R1), Classic Caddy Cover (9991794-R1) and Universal Caddy (9996084-ASSY). Each has a distinct part number and separate Maytronics detail page. Their placement as add-ons does not demonstrate that any comes in the box, fits this exact robot, or is the frame pictured with it. If a caddy or cover is important, get written confirmation for Product No. 99991036-SPLI and the seller's exact carton.

The page lists a three-year warranty. Before purchase, compare the warranty terms that apply to the exact U.S. offer and its serial number; the product table alone does not resolve service eligibility. It also lists two brushes and a “Combine Brush” type, but the lack of an applicable manual leaves care and replacement directions open.

How it differs from other 50-foot listings

The Sigma is not interchangeable with another Dolphin simply because the name or pool-length limit looks similar. The S400 page also lists three-area coverage and a 50 ft maximum, but its U.S. page shows a two-hour default with selectable durations and a delay feature; it does not identify an in-box Ultra-Fine kit. The Sigma instead lists a 2.5-hour default, no delay, and an additional Ultra-Fine kit in the box, while its app label and manual gap do not establish specific controls. Compare the separately researched S400 assessment rather than transferring its filter or schedule details.

The Premium 40 is another distinct corded, 50-foot, waterline-capable listing that names MyDolphin Plus and an in-box Ultra-Fine kit. Its own page lists a different default cycle, warranty, and caddy field. The Sigma page identifies an in-ground-only classification and does not establish caddy inclusion. Product numbers, package fields and page wording should decide the comparison—not a shared brand or similarly broad claim. See the separate Premium 40 assessment for its own manual and classification caveats.

Bottom line and exact-model checks

The Sigma is a reasonable evidence-based candidate to compare when you want corded operation, a manufacturer-listed 50 ft maximum, floor/wall/waterline coverage, app availability and an additional Ultra-Fine kit specifically named in the box. The main limitations are practical: the 50 ft figure is not cable reach; the page classifies it for in-ground pools only; app actions are not explained; a manual was not returned for its exact product number; and caddy inclusion, depth, step guidance, finish compatibility and safety setup remain unresolved. The page's active-brush wording is internally inconsistent.

Before choosing a seller, confirm the full U.S. Product No. 99991036-SPLI, obtain current model-specific instructions, verify the exact contents and warranty for that offer, and check the pool's measured length and layout against manufacturer guidance. No current price, stock status, product test, ownership, or customer experience is claimed here.

Sources: Maytronics' exact U.S. Dolphin Sigma page; its product-linked exact-number manual selector (no products found); and the exact page-linked Sigma image. The separately linked Premium Caddy Cover, Classic Caddy Cover and Universal Caddy pages identify separate parts, not Sigma carton contents. Comparisons use the separate exact U.S. Dolphin S400 page and Premium 40 page; none of those fields is transferred to Sigma.