my first cycle, almost through? water change question
 

First off, so happy to have found this forum. I had a tank during middle school while I had chronic migraines and it was a huge part of my life then. Being in middle school, I started up the tank pretty haphazardly, basically only researching the species I put in it and not anything relating to the ecosystem I was creating. I recently started working at a fish market and decided to get back into it! I can truly say fish are my life! haha!

So I have a 40 gal tank with a fairly large canister filter. Its been running for about two weeks, with 3 'Fruit Tetras' and 2 Serpae Tetras as my cycle fish. I have two live plants of different species. I'm very pleased with my LFS and only one Sarpae tetra has died so far, I noticed his top fin was picked at and then the next day the entire fish disappeared... assuming the other sarpae's ganged up on it... since I don't really want a school of sarpae's I probably wont go with them in the future.

As far as my cycle goes, I've been taking careful daily tests with my liquid API test kit. I saw the ammonia spike, did a decent 30% water change and haven't seen ammonia test since then. I skipped one test day this past weekend and last night saw a huge nitrite spike easily around 1ppm if not slightly higher and a decent presence of nitrate, ~10ppm. I did another 30% water change last night and after testing it this morning again the nitrite is still around about 1ppm and nitrate is somewhere between 5ppm and 10ppm.

I'm wondering if I should do a DRASTIC water change, like 75% or something like that. Being that I have a large canister filter (penn-plax 1000) I can't forget that there is a decent amount of the tanks water sitting in the filter as I do water changes, in a way diluting my water changes, correct?

I'm also seeing what you guys think of my progress so far. :-)

Welcome to the forum!
I'd do a 50% or so change, but realize that cycling a tank can sometimes take a month or more - patience!
Actually, your water parameters are not bad.
Check the water every other day, do changes as needed, but be really careful on the feeding. Feed about 1/4 of what you think the fish need, it will still be enough for them and will keep the water quality higher!
I know others here will offer some good advice for you also.

Again, welcome to TFK

Welcome to Tropical Fish Keeping forum.

Nothing to add to DKRST re the cycling. Will just mention we have fish profiles, second tab from the left in the blue bar across the top of the page, with info on many species. Serpae Tetra is included [you can also click on the name when it is shaded], you will see it is notorious for fin nipping and aggression, and needs a large group but that can limit other fish so you are proably wise to look elsewhere.

Byron.

Thanks guys, After my 50% water change earlier today my new readings are:
nitrite: .5ppm
nitrate: <5ppm

I'll check again tomorrow and do another 25% water change...

If you are getting .5 nitrite after the wc, I would do another. Nitrite must be kept below .25 with water changes. A conditioner that detoxifies ammonia and nitrite [it will still be available to bacteria, just non-toxic] is also beneficial during cycling; Prime does, and Ultimate too.

Presumably you have checked the tap water alone for ammonia, nitrite and nitrate; it is worth knowing if any are in the source water.

coming from my science background of course I did a test of my water before the whole cycle as my control group. All test at 0. Thanks, I'll do another wc this evening!