FLuval 403 -too much filteration??

with goldies, I doubt you'll be able to have too much filtration. Are these fancies? The more streamlined goldies will be fine with higher flow, but some fancies might need a buffer--you should be able to get a spray bar that would diffuse the output.

No matter what someone tells you or what you may read as a selling feature for a product, nothing takes the place of clean, fresh water. Water changes remove things that a filter cannot.I don't think you could add a pleco cause I believe they need warmer temps than your goldies.

Ditto boohoo on both points. maybe the guy was joking about the water changes.
I think buffer just means a way to break up or lessen the strong current before it hits the fishies.
I am not familiar with the filter exactly to tell you how to accomplish that. a spraybar would accomplish that.per OG and thery ARE sold at lfs.
good idea to overfilter the GF tank. Also go heavy on the gravel vacuuming/ partial water changes. If you are sucessful with these fish, I think the comet will eventuallygrow tool long for your 30

I have a 404 Fluval. Is the 403 an earlier model or just a typo? If it's very similar to the 404 than I would definantly say it will be fine. The fluval flow level has a regulator on it. There is a lever that controls the output and you could easily turn it down considerably to not cause too much current. The great thing about a filter that larger is you will hardly ever have to change the filter media, since it is much larger to accomidate a higher rate of contaminates coming in.

I kept the flow down to about half when it was on my 55g, a little higher now that it's on my new 60g.

BTW, they say 100 gallons max, but thats max...meaning you can use it on tanks 100g and smaller. Also, I think 100 gallons is a bit of a stretch, seems like a lot for this filter system. I plan on a Cascade filter system one day, they have a higher gallon rating.

My Fluval 404 is about 16" tall and about 7" wide, the canister.

There is nothing in my books called over filtration. You must remember that the aquarium is a closed environment. Unlike in a river, lake, or creek where new water is currently being replenished, and waste and other organic bi-products are blown downstream, the water in your tank is used and reused again until you do a water change. While no filtration system is 100% in a closed environment (unless you are the filter and do water changes constantly to simulate an open system), you can better achieve a healthier and more stable, environment inside your aquarium with more/efficient filtration.

Higher gallons per hour readings on filters do not necessarily mean more filtration is being performed. The degree to which water is filtered is dependent on the amount/type of media used and the design of the filter itself. With power filters (cascading/waterfall filters), waste water often bypasses the media in the filter all together and flows back into a tank. With canister filters, you can pretty much be guaranteed that all the water that comes out the end will be filtered. Power filters work well, but they aren't nearly as efficient as canister filters.

I've used a 403 for about 5 years before going to an Eheim...The only thing I can remember about that filter was that it was noisy and the O-ring was a pain in the @$$ to put back. Glad I made the switch

Hope this helped