Metronidazole, Kanaplex, Denitrate/Matrix Quesitons

[dtscheung]

Hi there,

I have a few questions on Seachem's product and would be grateful for advise.

Q1
Some of my fish are not eating and growing thin, and I plan to use Seachem's Metronidazole. However from online sources, they say Metronidazole must be used at 80-82F, lights turned off and dose 2x a day. Is Metronidazole light sensitive? Does it become inactive in 8 hours like people say online?

Q2
Some of the fish with not eating symptoms also shows Malawi Bloat signs like stomach bloating, and I read Kanamycin Sulphate is useful for treating internal bacteria. However, I was told the dosage for internal organ treatments require 100+mg/L daily to be effective. That is much higher than the 180mg (or 72mg) per 20L that Seachem is suggesting. Here are the two links I've obtained: http://aquascienceresearch.com/APInfo/DrugDose.htm and http://www.novalek.com/aquavet/kanamycin.htm

Q3
I currently use a wet/dry sump and plan to replace the sponges or foams that I have with biological filtering media like Matrix/DeNitrate due to my current very fast growing Nitrate level. The sump currently uses a 3500L/hour return pump. Water is drawn from internal overflow with prefilter and bioballs in the chamber before droping to the dripping tray in the sump with more bioballs. Under the bioballs are a previously placed 1L Matrix and at least 3-4L of ceremic Bio Rings. I still have 3-4L worth of media space after the existing media, and I'm wondering whether I should use Matrix or DeNitrate. Although the return pump is 3500L/h, I noticed the actual flow rate through the chamber given it's surface area is not that high as the chamber with the free space is against gravity going upwards before dropping back to the return pump chamber. Given the free chamber is also towards the end of the filtering process (less oxygen), I'm leaning towards using DeNitrate over Matrix, but I'm worried my wrong estimate re the water flow rate. Am I going towards the right direction?

Thanks in advance!

Daniel