Okay, so, I'm new here. I had a Betta fish for like a week, but unfortunately he died because of some bad advice from a store keeper (he tested our water and told us our cycle was complete--it wasn't and my fish died from what we think was nitrite or ammonia poisoning). Anyway, it has been roughly a month of my tank running and I think my cycle is actually complete now, as nitrites have gone back down. There aren't any nitrates in the tank for me to confirm this, but I have plants in there that will get rid of nitrates so that is probably why. I got a new Betta fish two days ago, and I have some concerns popping up regarding care and maintenance. I am completely new at fishkeeping, so bare with me, there are a lot of questions (Feel free to respond to only one of them or a couple if there is too much to respond to. Number 5 is kind of the most time sensitive question):
1. Replacing filter parts. I have a Fluval Chi 5 gallon tank, which has a unique filter system that makes a waterfall. It has a black "foam" pad in it (it looks more like steel wool to me but it is called foam) that I think is the biological filter that has the bacteria on it, along with a white foam pad that I think is the mechanical and carbon filtration. I have contemplated cutting the black pad in half so that I can change out half of my biological media at a time. Would this be a good idea? Also, about how often should I change out each of the filter parts?
2. How to clean my gravel. I do not have a vacuum or anything special to clean my gravel with, so how should I clean it? And how often?
3. Size and frequency of water changes. I have seen a lot of very different numbers regarding water changes. I was hoping someone could provide insight for what is best for my tank specifically. I have only 1 fish, 5 gallons of water, and 2 plants in it (I'm getting more plants soon). I have been doing 20% water changes weekly, but I'm contemplating bumping it down to every other week. Would every other week be alright?
4. Adding more gravel with a fish already in the tank. The amount of gravel/sand in my tank isn't enough for my plants, so I'm going to add more. Problem is, I have no idea how to do this with a fish and water already in the tank. I know I have to clean the gravel, but do I need to rinse it in dechlorinated water before adding it to the tank? How should I actually pour it in without harming the fish?
5. Covering the tank with a towel to decrease light. I live in a dorm, and my roommate leaves the light on really late, which is the only reason this is a problem. I turn the tank light on at 7-7:30 in the morning before class. However, the room light does not go off until 11-ish. That is only 8 hours of darkness for my Betta, which from what I've read is not enough. I have covered the tank with towels (it is awkward because of the waterfall filter, I'll post a picture later) to make the tank darker earlier in the day. Is this safe? The filter/a small part of the top is not covered. Is the oxygen going to be alright in the tank? I am monitoring the temp and it hasn't gone up from the towels (It's actually gone down from the darkness. My heater is broken, I have a new one coming in soon but for now I just bumped my room temp up really high.).
6. Weekends away from the tank. This won't happen often, only roughly every 1-2 months, but there will be 3 days where I am completely away from the tank. On the day I leave I could feed him in the morning and an early dinner, I would be gone for three straight days, and then I would be back the afternoon of the 4th day. So that is 3.5-4 days of my fish being alone and unfed. I've seen those vacation Betta feeder things that you just drop in the water and the fish supposedly eat, but they seem suspicious to me. I'm not sure I'd want to leave one unmonitored in my tank or if my fish would even eat it. Do these things work? I also don't have an automatic feeder, and I'm not confident my fish could find the food if it sank to the bottom before he noticed the feeder released it (he eats food from my finger when I feed him). Would my fish be alright to go that long without being fed? If not, what should I do?
I think that is all for now! I know it is a lot, but I don't want to lose another fish by making a mistake I didn't know was a mistake.