cleaned tank and now plecos are dying

[newfishmom1]

So I just did a 50% water change in my tank and put in a new plant, rinsed the rocks and put in fresh water. I have quite a good filter and the silt from stirring up the gravel was gone within 30 minutes. I have 3 fish in the tank for the time being: a 4-inch goldfish, a 4-inch albino bristlenose pleco, and a 3-inch pleco (maybe zebra, maybe common). As I was cleaning the tank the albino guy kept swimming up to the surface very quickly, making a big splash and then going back to the bottom. Now 2 hours later the tank water looks completely clear and the albino pleco is very dead. I'm worried about the other little pleco, he's my last remaining pleco and I don't want to lose him too. What could I be doing wrong with cleaning the tank because I've read so much about tank cleaning and water changes and I think I'm following all of the rules, but every time I do a big tank clean some of the fish die. Last time it was two big cory cats that I got with the tank, and I don't want the pair of plecos to both die as well. I've already lost the big one, and I'd like to have a mature small one in the tank.
I'm just quite mad at myself because I thought I was past the fish dying randomly phase of being a new tank owner but I guess I'm not. I'm quite sure that It's my fault though and I've done something horribly wrong and keep contaminating the tank.

 

[Colin_T]

Do you use a gravel cleaner to clean the substrate?
You should use a basic model gravel cleaner to clean the gunk out of the gravel. It removes water at the same time. If you don't have a gravel cleaner, you can make one from a 1, 1.5 or 2 litre plastic drink bottle and a garden hose. Cut the bottom off the bottle and remove the cap, throw these bits in the bin. Stick a garden hose (or plastic hose) in/ on the top and run the hose out the door onto the lawn. Use the bottle to gravel clean the tank.
The following link has a basic model gravel cleaner.
https://www.about-goldfish.com/aquarium-cleaning.html

Do you dechlorinate the new water before adding it to the tank?
Any new water should be free of chlorine/ chloramine before it's added to the tank.

 

[newfishmom1]

I have a motorized gravel cleaner which I got from the lady who sold me the tank. I had to clean the gravel every week or two until I got this new filter from my aunt. I've had it in the tank for the past 4 months and haven't needed to clean the gravel at all. I know that the plecos need algae to feed on so I'm trying to increase the amount of green stuff they get since the tank is so much cleaner now.

I had our water tested by our pet store and they said that our tap water is perfect for fish and no need to treat or do anything to it. I live in central Texas and we have extremely hard water (there's a ton of minerals in it) which made what the pet store said seem odd to me but I trusted them on it. I guess they may have been incorrect?

 

[Colin_T]

motorised gravel cleaners are a waste of money that do nothing to help clean a tank. If it's the type with a mesh bag that traps the gunk and recycles the water, they are actually bad for the fish.

you only need a basic model gravel cleaner and should use it every time you do a water change (each week). The idea of a gravel cleaner is to remove the gunk from the gravel, and to do it without releasing anything into the water.

 

[newfishmom1]

okay I see how that would be different. Yes it is the one with the mesh bag. If there isn't any gunk in the gravel do I still need to clean it out it each week? Same question for the water: if the water stays clear do I still need to do changes?

The filter that I have is the one that stays under the tank in a cabinet and has hoses to the intake and output tubes. I've raised the output one out of the water a bit so it makes lots of bubbles and oxygenates the water. From what I read that may help the remaining two fish with stress from a bad water change?

 

[Colin_T]

Water changes and gravel cleaning should be done every week or every 2 weeks. But it needs to be done regardless of if the water and gravel looks clean.

I recommend doing a 75% water change and gravel cleaning the substrate once a week.
If there is any ammonia or nitrite in the water, or a nitrate reading above 20ppm, then do a 75% water change and gravel clean.
If you ever lose a fish or the water goes cloudy or the fish look unwell, do a 75% water change and gravel clean the substrate.

-------------
You do water changes for 2 main reasons.
1) to reduce nutrients like ammonia, nitrite & nitrate.
2) to dilute disease organisms in the water.

Fish live in a soup of microscopic organisms including bacteria, fungus, viruses, protozoans, worms, flukes and various other things that make your skin crawl. Doing a big water change and gravel cleaning the substrate on a regular basis will dilute these organisms and reduce their numbers in the water, thus making it a safer and healthier environment for the fish.

If you do a 25% water change each week you leave behind 75% of the bad stuff in the water.
If you do a 50% water change each week you leave behind 50% of the bad stuff in the water.
If you do a 75% water change each week you leave behind 25% of the bad stuff in the water.

Fish live in their own waste. Their tank and filter is full of fish poop. The water they breath is filtered through fish poop. Cleaning filters, gravel and doing big regular water changes, removes a lot of this poop and makes the environment cleaner and healthier for the fish.

--------------------------
The filter that sits under the tank and is connected to the aquarium by plastic hoses is an external canister filter. These should be cleaned at least once a month, and the filter materials should be washed out in a bucket of tank water.

Raising the filter outlet above the surface does help to increase oxygen levels in the water and this can help fish recover for illness or poor water quality or poisoning.

Using an air pump and an airstone will also help increase oxygen levels in the water.

 

[FishGuest5123]

Are you using dechlorinator? You still need that. I’m in Texas too.

 

[newfishmom1]

Update: little pleco has resumed normal behaviors and seems to be okay.

Thank you all so much for the help, I feel awful that I hadn't figured this out before I accidentally killed three fish but I guess that's my fault for buying a tank with fish already in it. I'll definitely be back with more questions though!