A Question Re: Filtration, Water Changes, And Tropheus Sp.

[BrownBullhead]

A question re: filtration, water changes, and Tropheus sp.

I feel a li'l sheepish, dumb, whatever, in asking this question, but I am quite curious to see the opinions I will receive, so here goes.

For an "established" (running longer than 6 months) aquarium, 150-gallon, filtered by a Rena Filstar xP3 w/ 2 of 6 basket trays filled with biological media, and also filtered by 3 x Hydro-Sponge #3 sponge filters, my question relates to water changes...

Is it required to maintain 50% weekly water changes in a tank this size (75 gallons per week) when only 16 Tropheus Moorii Nkonde of 3.5" to 4.0" inhabit the setup?

I would like to think I could cheat a little because of the sheer volume of water versus the amount of waste produced by 16 fish. What do you people think?

 

[CFC]

Water changes can be judged by the ammount of nitrate that builds up in your water. Test the nitrate level in your tapwater, in most cases this will be between 10 and 40ppm, your aim is that the water in your tank has a nitrate level that does not exceed 20ppm greater than that in your tapwater in the time between water changes, if this can be maintained with a 10% weekly change then that is all that is needed, if the nitrates in your tank are more than 20ppm greater than the nitrates in your tapwater then larger water changes are needed. Most tanks are fine with water changes of 10 to 20% weekly but those that contain largeo or messy fish or are heavily stocked will probably require 40 to 50%.