How big is your tank because unless it's really huge, an Oase Thermo 850 combined with a 600 is way over filtering.
The Dirty Truth About Filters is that although they make water clearer, they don't make it any cleaner. Trapped detritus just decomposes and pollutes the water. It's a hobby myth that gets repeated that "there's no such thing as too much filtration" ... but there is! A much better truth is that 'there's no such thing as too much fresh, clean water'.
Not even to mention that the Oase Thermo 850 retails for $450 USD and the 600 is at $388. That's a chunk of change for filtration.
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As to installing a new filter, it is a hobby myth that beneficial bacteria only lives in the bio-media inside a filter. Promoted no doubt by the marketing from manufacturers of relatively expensive bio-medias. In reality, in an established tank (6 months or longer) there is actually more beneficial biology in the tank, especially in the substrate than would be found in any filter. So you could swap filters and never see a problem.
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For extra credit, check out
Cycling a New Aquarium.
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footnote: I'll admit that years ago I bought into the marketing hype that we need commercial bio-media to provide a suitable platform for beneficial biology (at least nitrosomonas and nitrospira to process ammonia and nitrites into nitrates). But after years of experimenting and pondering the questions of life, I came to realize that sponge material was not only excellent at mechanical filtration, but also as a platform for BB...as evidenced by the many large fishrooms powered only by air driven sponge filters. So all of my filters are totally filled with sponge material. Sponges are easily cleaned and last nearly forever. There is one exception, I'm experimenting in the 45g sump on my 110g stock tank (colony breeding red Swordtails) with Dr. Kevin Novak's
Anoxic Biocenosis Clarification Baskets.
Wel abbeysdad I’m too late now lol.
I didn’t bother setting up both filters.I took the bio from the 600 and transferred it into the 850.I now have a 600 sitting doing nothing,but hey ho.Tbh I don’t really see any difference apart from size.The flow rate is obviously a bit more,but apart from that...........even that doesn’t convince me it turns over the water any more than the 600.
The set up is exactly the same as I had it before I “upgraded”.
I didn’t bother installing a spray bar,who needs them noisy things.The water flows straight out without a lily pipe.I have a powere head,it’s strong enough,and a bubbler directly below it,which the power head shreds into dust size bubbles so that’s a big plus for me,but I already had that anyway hahaha.
The 600 has 6 trays,2 for bio,3 for thick coarse foam and the last which is another thinner coarser foam,and the prefilter is 6 pieces of dense foam.
The 850 has 7 trays,again 2 for bio,4 with coarse foam and again the same as the 600,a thin coarser foam.The main difference for me is the prefilter which now has 6 pieces of coarse foam instead of dense foam.
Now I don’t know what the difference is in flow rate,but I feel oase have conned me,because if I had just changed the dense prefilter foam in the 600 to a coarse foam,maybe it would have helped up the flow rate,turn over,whatever one wants to call it,hmmm.
The heater is 400 watts,so I’m sure that’s bigger.I paid £260 for the 600 and £300 for the 850,was it worth it
My tank is 413l,not sure what that is in good old US of A gallons,100 odd maybe,you will know.
I bought the tank last year,it’s an oase and it has the built in outlet on the bum of the tank,so the filter was made for it basically.
The system as a whole is excellent,but if that outlet o-ring rots or gives way I will have a healthy clean up to undertake haha,it makes me nervous.
When I was a lad I had a wee tank with a box filter that lay on the bottom,filled with cotton wool and it blew out a bubble now and then,oh how things have changed,if someone had mentioned that it had to be cycled I would have asked them where the pedals were.
Cheers again for the advice,cheerio the noo.
