filter and tank question

[geosyd]

hi - i have a question about fish tanks and filters in general -
*if you have a 3 foot/120litre/30gal tank and you have-
a 1500LPH With UV CANISTER FILTER -$85.00 http://www.guppysaquariumproducts.com.au/internal-external-filters/pro-aqua-canister-filters/1500l/h-with-uv-canister-filter-with-all-filter-media-new/prod_28.html - small bioballs removed and replaced with larger bio balls - one pack of carbon removed-one remaining plus added noodle bagsx2.
a Aquaclear 200 ( 50 ) Hang on Filter 250LHP - $ 65.00 http://www.aquariumproducts.com.au/catalogue_products.php?prodID=2886&catID=4 - sponge untouched - carbon removed and replaced by mini-bioballs from canister.
a JHJ-922 950lph internal power filter - $ 25.00 http://www.aquariumproducts.com.au/catalogue_products.php?prodID=3776&catID=3 '''wool type'' pad plus sponge filter media

*would this type of filter system reduce the amount of water changes required weekly.
i have had this system running for 3 months- canister arrived 2 weeks ago...
i'm also thinking of getting another small filter so i can have reserves in future plus a cleaner tank in general.
HY304D ( 1000lph ) $ 45.00 - top filter - media not included..http://www.aquariumproducts.com.au/catalogue_products.php?prodID=3348&catID=83
has anyone owned or does own a top filter, small or large - and suggestions...

just to add - this tank is home to two 4/5 inch tiger oscars for 5 weeks. in a few months i will be changing their tank into either a 5 or 6 foot tank, but i lack the room for that at the moment. i change 2 buckets from the tank every week as garden fertilizer. but i will reduce this soon- as i want to see if my filter ever will get dirty-i feed them hbh oscar show pellets / generic medium sized pellets-dipped in liquid super amino - dymatize nutrition orange flavour /frozen bloodworms-brine-krill/live garden worms-/ self-bred guppies and baby snails[they keep the snail population under control in a 30 litre tank] - i cant feed neons - they wont breed... lol

*when it comes to oscar nutrition- do they need/can they utilize/use growth hormone/igf's suchas/eg growth hormone releasing peptide solution dissolved into medium/large pellets...

im considering buying the following canister filter just before i setup my 5or6 foot tank...
2000L/H With UV CANISTER FILTER $99.99 - http://www.guppysaquariumproducts.com.a ... d_311.html
*would all the filters above-together be enough for a 5 or 6 foot tank.

[Tom]

How much filtration you need depends on how big the tank is.
Canisters should turnover 4 times the tank volume every hour.
Power filters (Hang on Back or HOB) should turnover 10 times the tank volume every hour.
How much filtration you have has nothing to do with how often you change the water (or how much water you change).
Water changes should be linked to nitrate levels.
Whenever nitrates exceed 20 ppm, change as much water as possible.
For a typical adult Oscar in a 50g, we recommend a minimum of a 50% water change every week.

[geosyd]

yeah thnx Tom - what do you think about the top filter - is it necessary/will it make a different with the nitrate levels/will it make a difference at all in any way...
what media should i get for the top filter and is there a type of media that will reduce nitrate levels..

[Tom]

No filters reduce nitrate levels.
The only way to reduce nitrates is by removing them by way of water change.
Your filters primarily provide a place for bacteria to live, along with some mechanical filtration.
Those bacteria change waste to nitrate, and nitrates continue building up in the tank until you remove them with a water change.
There are no additives that will make them go away.
Only you and your Python (or whatever method/device you use for water changes).

(Actually there is a device called a denitrate filter, but you need an in depth understanding of the nitrification process to get them to work)

[geosyd]

so something along the lines of this diy project would work...
http://www.ultimatereef.net/forums/showthread.php?t=387870

have you done anything like this before , and wouldnt it work better with a canister - fill the media with seachem De Nitrat/

[Bloodmourn]

The key is the gph. You want a slower gph, which is why they don't use a canister filter.