Hey everyone. This is my first post so please be gentle :P
I have a 30 gal
glass hex tank with a Penguin Bio-wheel HOB
filter that for the last 3 months held two very healthy goldfish (a Comet and a Fancy). I figured and the tank should have by all means been cycled after 3 months (wasn't a new tank before this either; the tank has had fish in it, albeit not the same ones, for 4 years while I was away at school---my mom loves goldfish). Anyways, I decided to get a common pleco since the tank tends to grow algae since I live in sunny, sunny California. Unfortunately, two things went horribly wrong. The addition of this new pleco seemed to have un-cycled my tank since I noticed first on my comet goldfish (he's white) the red streaking and stressed behavior indicative of nitrite poisoning about 3 days later during the weekly water change. So that's bad enough, but the next day I noticed small granular white spots developing on the fins of my fish, and after some internet research, concluded it was probably ich. Fairly certain it got carried in on the pleco (no quarantine tank) since this tank has NEVER had a parasite of any sort; mostly fish would die when my mom got lazy and didn't do water changes. I decided to start using Kordon Rid-Ich Plus since it seemed pretty severe, but I read around and worried that the pleco, being a catfish, would be sensitive and so have been giving half-doses as per some forum recommendations for "scaleless" fish (1/2 tsp per 10 gallons instead of the 1 tsp per 10 gallons). This treatment seems to be working (with daily 25% water changes & gravel vacuuming) as my goldfish are loads better and have been spot free for 4 days now. However, the pleco still has around 5-7 white spots that have been there and have not moved for the last 5 days, a few of which are on his eye, which to me seems odd since individual spots I was tracking on the goldfish disappeared in a matter of only 2-3 days.
This leads me to my questions... It has been 8 days since I started the Rid-Ich half-dose treatment; my tank stays between 75-78 F; is it normal for ich to take this long to clear up? I was under the impression the full cycle should only be about a week, with the trophozoite stage only lasting about 3 days. Was I wrong to half-dose and should I now scale up the treatment to the full dose of 1 tsp per 10 gallons? Or just be patient and continue with the half-dose? I am fairly certain it is still ich, since the other two fish responded well to the ich medication and the spotting on the pleco has definitely decreased despite these stubborn few.
Thanks all! :]