I'm a freshwater beginner

I'm a freshwater beginner. I have a 40 gallon breeder for the past 2 months. In the aquarium I have plants ,mystery snails, giant danio, gourami, german blue ram, tiger barbs, buenos aires, dwarf gourami and kribensis. I go to my local fish store and they check my ammonia, ph, nitrite and nitrate for free. They love my tests. I had cloudy green water and I took care of that with Fritz algae clean out. This weekend I have cloudy water, so I did a 50% water change (which I saw on youtube) and added Prime after. Why did I do that ...after the water change...fish started dying. Total lose 8. I went to the fish store with a water sample and everything was perfect. The fish was gasping for air. To add insult to injury the cloudy water is back. I have a Marineland Magnum filter and a DIY sponge filter. Should I ever do a 50% water change ever again and how can I get my water nice and clear. Please help. Thank you

 

Welcome to fishlore. Sorry about your loses. First thing I’ll recommend is you get your own test kit. Look on eBay/amazon. Get an apI master kit. I’ll bet your water isn’t fine. By your name I’m guessing your from Brooklyn N.Y. if so you should have great water out of the tap. So something else is wrong. How many of each fish do you have. What type of filter. Name and type and number if there is one. Some of the fish you chose do not belong together. Cloudy water usually means a bacterial bloom. So we need to find out why that is happening.

 

Cloudy water could mean anything. A possible bacterial bloom due to a week colony of beneficial bacteria. It could also be the start of an algae bloom. As far as 50% water changes.... that's minimum in my regimen. I usually do 60- 80 % weekly. You may have shocked them with temperature. Too cold or too hot when refilling?

 

Doing a 50% water change and using prime should never cause fish to die, in my experience anyways. I just did an 80% change in my 20 gallon yesterday because I had to move it onto a stand I built for it. So the reason the fish are dying has to be something else. Did you make sure the water temp was the same when adding the new 50% of the water? Fish are very sensitive to sudden changes in water temp so if it was a lot colder or hotter it may have shocked them? I'm just trying to think of ideas.

 

Welcome to fishlore. Sorry about your loses. First thing I’ll recommend is you get your own test kit. Look on eBay/amazon. Get an apI master kit. I’ll bet your water isn’t fine. By your name I’m guessing your from Brooklyn N.Y. if so you should have great water out of the tap. So something else is wrong. How many of each fish do you have. What type of filter. Name and type and number if there is one. Some of the fish you chose do not belong together. Cloudy water usually means a bacterial bloom. So we need to find out why that is happening.

I have test strips. I have 6 tiger barbs, 3 gold gourami, dwarf gourami, Opaline gourmai, 4 buenos aires, 2 kribensis and german blue ram. I'm running a marineland magnum polishing internal canister.

 

I usually stick to 30-35% water changes, But I do larger ones occasionally. It is important to try to keep the temperature stable. I keep an eye on my digital thermometer while adding water back in with my python/sink attach gravel vacuum. But I think it would take an extreme temperature change to kill them. Was there a possible contamination? nail polish remover/ lotion? IDK.

Some of the fish you listed would not have thrived together very long, so maybe you should not replace them right away.
What fish are left? How long has the tank been running? what were the actual results of the tests for ammonia, nitrite, and nitrate?
I would not use algae remover ever again. Your tank is getting established, cloudy water, green water, brown algae, its just the tank settling itself.

 

Those were the fish left. What I lost was 5 giant danios, pearl gourami and 2 otos. IDK if there was a contamination. ammonia was light green but my nitrites and nitrates was perfect

 

The pearl gourami is a sensitive fish, but the danios should be very hardy.
I think maybe -
1.You have too many fish for such a new tank.
2.You should never have multiple species of gourami, as they often clash.
Tiger barbs are rambunctious, semi-aggressive, and may become a problem for the other species. Keeping a larger school of 9 or more tiger barbs will help curtail their aggression, and keep things like tail chasing withing the species. But the gourami may become stressed and not do well long term with such active boisterous tankmates.
At the very least I suggest you rehome the dwarf gourami and maybe also the ram before it is too late. You need to consider returning the Buenos Aires tetra. The tiny fish will struggle to get their fair share of food amongst the other, larger faster fish.

 

Well you don’t have many fish left so your all right with numbers. I have Buenos Aires tetras and mine are about 3” long and they should be fine. As stated the tiger barbs will be a problem to your gouramis. So you know you have some problems with the fish you have. Next that polishing filter is not the right filter and probably your problem. Yes it can be used as a regular filter put it’s purpose is to polish. And it’s great at that. Online buy a marineland 350 bio-wheel. Usually sells for about $25-30. If you can afford better get a tidal 75. Having ammonia and no nitrate means your tank isn’t cycled. If your using the cartridge on that filter there is no place for bacteria to grow and if using it correctly it still doesn’t have enough space. I have this filter it’s a great polishing filter and in an emergency can be used as a regular filter till you fix or replace your broken filter.
Remember pet stores good bad or indifferent all are just moving product. Yours has giving you some bad choices if they directed you.

Oh and the German blue ram needs a temp of 82-84.

 

One thing that concerns me is that you said you added freshwater then added prime. I normally add the prime to the new water before adding it to tank. The other thing is if the ammonia reading is green that seems high if this is the liquid test kit which might suggest for some reason the tank isn't properly cycled (even if it is 2 months old).

Another thing that is critical with certain fishes (like german blue ram) is the new water has to be the same temp as the tank water. If the temp drops too much when you add the new water it will shock more sensitive fishes and kill them.

What temp is the tank ?