Although iRobot Scooba has been around for some time now I'll shortly explain you what it is and what it can do in case you're not aware of this household robot yet. Roomba's sibling Scooba is a floor washing robot that was first released in late 2005. It resembles Roomba in looks, the way it interacts with users and the way it approaches it's job.
Scooba cleaning principle. Photo courtesy of iRobot company
Although there are three successive Scooba generations, as far as I know the basic floor washing principles and machinery have remained largely unchanged until the last model. Initially the robot preps the floor by sweeping up loose dirt. Then it continues with washing - the clean washing mixture is applied. After that Scooba scrubs the floor using a rotating brush. The last step is squeegeeing after which the floor is nearly dry (or slightly wet, depending on how you look at it) as the squeegee sucks up dirty cleaning mix as well.
After this 4-stage cleaning the end result is quite good. This is the main reason of this household robot's popularity - it does it's job pretty good. Different iRobot Scooba models in the same generation usually differ with the area covered in one charge and with one fill-up. Obviously, cheaper robots can cover less while more expensive ones of the same generation can cover more although the sizes are similar.
There are also some other differences between some models in the same generation and differences between models of different generations. I'll try to explain these differences by discussing different generations and models within these generations seperately.
First generation Scoobas were designated with 5xxx model numbers. Namely these were iRobot Scooba 5900 and 5800. Although these robots are usually regarded as one generation, I think of them as first and first and a half generations, because 5900 was discontinued in favor of 5800.
5900 was the first Scooba model realeased. It saw daylight in Christmas season 2005 with full production starting in 2006. The robot could clean up to 500 square meters in one charge. Special cleaning solution with particular conductivity characteristics (Clorox) had to be used with this first model (later water+vinegar mix was approved by iRobot).
Supposedly the robot didn't sell as good as iRobot initially hoped. Partly because of its price, partly because it had to be used with the above mentioned cleaning solution which meant regular costs. Also, battery problems haunted the robot. Still, the robot did a good job when it worked.
To overcome these problems a new model , Scooba 5800, was introduced in the second half of 2006. It had improved software and updated battery maintenance instructions to ensure better battery operation. Also, to cut the price it came with fewer accessories and it could clean less - 250 square meters per charge.
What's very important - model 5800 was the first model that could be used with plain water. Also, to rectify battery problems of early Scooba 5800/5900 robots a software upgrade - OSMO was later realeased.
iRobot Scooba 380. Photo courtesy of iRobot company
Although usually second generation iRobot Scoobas are designated with 3xx model numbers not all 3xx robots are second gen robots. There was a time when re-branded 5800 were sold as 330/335/340, similarly how older generation roombas are sometime sold as entry level machines when the next generation is released.
Second generation models are 350, 380 and 385 where 385 is a localised version of 380. Sometimes you'll also see these models called Scooba 6000 (350) and 6050 (380). It seems that this latter naming follows the previous 4-digit pattern. The "proper" names are 3xx ones though.
I suppose you want to know where's the real difference between 5xxx and 3xx Scoobas. As I said, the main floor cleaning principle was not reinvented. Supposedly, second generation models are better built and use better materials to improve longevity.
The main difference is movement speed though. Second generation models move faster than 5xxx models thus laying less cleaning solution on the floor (while still doing a good job). This in turn increases floor coverage. So, basically, 2nd gen models can clean more in the same time.
Speaking about floor coverage. Manufacturer's specifications say that 350 can cover 500 square feet per charge while 380 can cover 850 square feet per charge. However, you have to bear in mind that the area covered before a tank refill is required is twice as less - 250 and 425 square feet accordingly.
There are no other major differences between these robots as far as I know except the package contents. Scooba 380 comes with two virtual walls while Scooba 350 with one. They weigh the same, they are equally large, both can use either clean water, water + vinegar mixture, or Scooba Hard Wood Cleaner.
iRobot Scooba 230. Photo courtesy of iRobot company
The latest iteration of the iRobot Scooba product line - Scooba 230 is the most innovative, except for the first Scooba of course. At the moment it is the only 2xx generation robot and I haven't heard anything suggesting the development of other 2xx models.
It wouldn't be much of a surprise if iRobot Scooba 230 was the only "third generation" Scooba, as at this moment it seems that it's not made to replace existing Scoobas. Rather it comes as a much anticipated addition to the family filling a bit different niche.
Imagine the scenario - someone has an apartment that Roomba takes good care of yet there are a few places that still *has* to be moped - bathroom, maybe a tiled area somewhere, etc. There's no point in buying a Scooba that's too large to clean the tight spaces with that price tag.
This is where Scooba 230 come in. At just 6.5 inches in diameter it's considerably smaller than its larger cousins. This is mainly achieved by clever design. If older Scooba models have two fixed volume tanks for clean and dirty solutions, Scooba 230 has two variable volume bladders. When the clean solution is being used its bladder size shrinks allowing the dirty solution bladder to expand.
Also, maintenance is made easier. In this model cleaning brushes, the squeegee and suction ports are housed in one bottom plate that can be easily removed and cleaned. Also, the bottom plate can be just as easily replaced when needed to avoid performance loss due to wear and tear.
The robot comes with three spare bottom plates, two virtual walls and 4 packets of Scooba Hardwood Cleaner. It can be used both with Scooba Hardwood Cleaner and plain water. Almost forgot - it can cover 150 square feet in one run.
As you now know iRobot Scooba has its history. First Scoobas were not without major issues, some people say for 3xx longevity is still a problem. Some people sometimes get defective units. However, the robot is still here and is carried by many vendors.
The reason is quite simple - it makes life easier and does a good job when it works. What to do to ensure the robot will work for you? First of all the operation manual and maintenance instructions have to be meticulously followed. From time to time it's also good to overhaul the unit with new spare parts. For example, the wheels of 3xx models tend to wear out from time to time.
How to assure yourself against a possibility of getting a defective unit or something defective in the package? Well, I would buy a used Scooba only if I was sure of its history, or if it's really cheap. If you buy new - make sure you buy from an authorised reseller to ensure you can benefit from manufacturer's warranty. So, iRobot corporation's official store is one good option.