OASE BioMaster 2 Thermo 350 Review: Worth the Price?

A canister filter with the heater inside it and a pre-filter you can clean without opening anything.

The verdict: Buy it if you keep a display tank up to about 90 gallons and you want the heater out of the water column and the weekly maintenance down to pulling one module. Skip it if you already own a working heater and a working canister, because the price premium over a Fluval 307 buys convenience rather than better filtration.

Specifications

Specifications above come from OASE's published product information. Treat pricing as approximate, since Amazon pricing moves.

What it does well

• The EasyClean pre-filter is the reason to buy this filter. Most routine cleanings become a two minute job that never disturbs the biological media, which is exactly the media you should not be disturbing.
• The heater lives inside the canister, so the display holds no heater and no fish can rest against a hot glass tube.
• A four year warranty on a canister filter is unusual and says something about how OASE expects the pump to hold up.
• Safety locks on the handle, pre-filter and aquastop mean routine maintenance does not end with water on the cabinet floor.
• Rated for saltwater as well as fresh, so it moves with you if you switch the tank over.

Where it falls short

• The integrated heater is controlled by a bi-metal thermostat, which is the same basic mechanism as a traditional glass heater. It is not a digital controller with an external probe, and a stuck bi-metal contact is the classic way a tank gets cooked. If you keep anything valuable, a separate temperature controller is still worth having.
• You pay a real premium over a plain canister of the same capacity. The filtration itself is not dramatically better than a Fluval 307, and the money is buying the pre-filter and the heater.
• The 90 gallon rating is a manufacturer ceiling, and as with every canister it assumes light stocking. A messy 90 gallon tank wants the 600 or the 850.
• Servicing the heater means taking the canister apart, which is a longer job than swapping a heater in the tank.
• Replacement foams and Hel-X media are OASE parts, so budget for them rather than assuming generic pads will drop in.

What owners report

Published owner reviews converge on the pre-filter almost immediately. Keepers describe it as the feature that changed how often they actually clean the filter, because removing one module and rinsing one sponge is a small enough job to do every couple of weeks. That habit is the real benefit, since a filter serviced on time holds flow far better than a superior filter serviced late.

Owners also consistently note that the built-in heater keeps the display clean, and just as consistently note that they cannot see the heater to check it. Several report adding an independent thermometer or controller for exactly that reason. On the negative side the most common theme is priming and the initial setup, which several owners describe as fiddlier than a Fluval, and the price, which comes up in almost every review whether positive or not.

Sizing it, and the heater question

Rated capacity and useful capacity are different numbers. Work out what your tank really holds with the aquarium volume calculator, then check the turnover you would get from this filter using the filter turnover calculator. Separately, confirm the integrated heater has the wattage your room needs with the heater size calculator, because an underpowered heater in a cold room runs constantly and wears out early. If you are still deciding whether an in-tank heater would suit you better, glass versus electronic aquarium heater covers the trade-off, and canister filter versus hang-on-back covers whether you need a canister at all.

Who it suits

• Aquascapers and display-tank keepers who want nothing visible in the water but plants, hardscape and fish.
• Anyone who knows they neglect filter maintenance and would benefit from a cleaning job that takes two minutes.
• Keepers running 40 to 90 gallons who value quiet, tidy operation over raw flow numbers.

Who should skip it

• Bargain hunters, since a Fluval 307 filters a similar tank for well under half the money.
• Heavily stocked tanks at the top of the rating, which should step up to the 600 or 850.
• Anyone who wants precise digital temperature control, who should pair any canister with a separate controller instead.

Alternatives worth considering

Keep reading

• Canister filter vs hang-on-back
• Glass vs electronic aquarium heater
• Heater size calculator
• Best canister filters
• Fluval FX6 review

This review draws on published specifications, manufacturer figures and the consensus of verified owner reviews. We have not tested this product ourselves, and we say so rather than implying otherwise. As an Amazon Associate we earn from qualifying purchases.