I can't add a different substrate, my dad won't let me otherwise I would. The temp is usually around 78F to accommodate for everyone's needs. I just wanted to avoid being lectured, sorry if that sounds silly but that was the reason.
Don't look at it as lecturing, if someone takes the time to reply, they do want to help you. The more people that reply, the better the catalogue of knowledge you can aquire. There is ALWAYS more to learn/ improve when keeping fish, that's the point of posting to a community for the consensus!
If you were avoiding being 'lectured' then you must have had a fair idea you were going wrong somewhere, don't be embarrassed or take suggestions too personally when they don't apply or aren't feasible right now, as long as you're trying your best that's the important thing.
I wouldn't rush into more cory's if it's only them that struggle, although your lonely one will need companions of the same species, I don't think now is the time either.
No one will judge you for just explaining that funds are tight, you don't have to excuse yourself, but I agree with other posters that the photo of your water is a horrible colour. If it is the water rather than camera this is something that Needs to be fixed with large temp checked water changes.
I would remove some tank water to a clean/ new bucket and put the fish in that for an hour to give you a chance to clean glass & do a 90% water change, add as much sand as you have, using the above suggestions about laying it & some sort of border to separate the two( when adding water pour it on the already settled gravel, so as not to stir up the sand more than needed, I usually pour all the new sand in a large bucket first, or batches in a smaller one, and just run my fingers and the tap through it for a good amount of time to clear as much dust as possible) Follow up with at least 25% every 3 days for a fortnight, continuing with 50% per week.
Be careful when washing your hands (before reaching in water) & with what you clean things with, (washing up liquid, liquid hand soap, moisturiser, perfume, bleach residue and tap water will all harm if not kill your BB and fish) white vinegar is a good (cheap) cleaner for algae (on removable rocks/ decor, tubes) and it's easy to soak off the residue in fresh water (careful it also kills moss). Aquarium salt water is good ( & reasonably cheap/ cost effective) for cleaning plants before they go in tank to kill off any hair algae/pest snails.
It is also possible to treat freshwater fish for mild bacteria/fungal infections with aquarium salt, the Cory in photo looks extremely pale/ underweight to me, I don't know if it was like it from the start, but it is definitely a sign of stress. What sort of light do you run?
Should aquarium salt be used in freshwater tanks? After years of testing, we believe salt is one of the best, all-encompassing fish medicines on the market
www.aquariumcoop.com
Plants could also be very carefully bleached with the right ratio to water, for no longer than 3mins however it is riskier and I always soak them after in two lots of clean tap water, and then one soak in removed tank water before they go in.
It is always a good idea to wash anything before you put it in, just google the most appropriate method, like boiling new driftwood.
Cycling a new tank is a lot easier if you already have a mature tank, although I'm not sure I would start the 5g with substrate from unstable community until you know what's up, maybe pinch some substrate from your parent's tank, or assume taht you have to start the "fish in" cycle again anyway?
What foods do you give the community, less is usually more with fish, try smaller more regular meals if the algae is taking over, and you can always do a "blackout" if it gets out of hand. I use "stick on glass" shrimp/ algae wafers once a day to count my cory fry & check the underside, barbels & general health of Corys and pleco, they also help keep the food out of the gravel/ on the beach end for cory's to filter feed, it is very easy to see if you are over/ underfeeding (I give my cory's just enough that they can finish in 30mins, at least 3 times a day, or 20 mins 4 times a day, including a variety of foods) my window tabs come from "norfolk feeds" there is probably a different brand in the USA though. The rest of the fish (pleco excluded because she is supposed to be nocturnal so I wait til everyone else sleeps) get just enough of their specific foods that they can eat in 5mins 3 times a day, leaving as little waste in water as possible. I also give all but the fry a starve/ fasting day every Saturday a day before tank cleaning so the algae eaters get a chance to clean/ fill up before I clean the glass.
I agree about how useful it is to have an API test kit, but even your local pet chain should be able to test water for you (just explain you are still cycling in preparation for new fish) while the freshwater kits aren't in stock.
You won't get different answers by posting more, as the dedicated & experienced (I don't consider myself anywhere near as knowledgeable, but I understand problems with the purse strings!) fishkeepers that are always reliable when we need help, all know their stuff and need complete info ( for best diagnoses not judgement) or will make similar 'default' suggestions. We have all made costly mistakes while learning to keep our fish tip top, it's the learning from them that counts!
If you have genuinely tried everybody else's suggestions, perhaps the pet store chain just have bad cory stock, try looking for listings from experienced local hobby breeders once you are confident conditions are good again, they are more likely to have been cared for/ bred better in my experience.
Excuse my massive essay, it is supposed to be reassuring so sorry if you've just had enough of suggestions! Feel free to message me if you're just feeling the lonely despair of feeling like you've failed your fish. I understand, I lost an endler at the weekend after having to wait 2 days for a new filter impeller( which cost me £7 for supposedly next day postage!), despite adding bio media to tank in mesh bag, chances are I lost most of the bacteria in canister as the little filter I improvised just didn't have the flow required to keep bacteria happy. I don't know it was related as the parameters have been fine, could have been a coincidence but there is always something that makes you wonder if you could have tried more!
I wish you luck in your future endeavours, don't give up if you still get pleasure from tank, just be patient about getting the eco balance right, bedding in your plants and caring for existing fish
