Tank emergency!!!! betta stripes and dying!

[RoseyD]

ARGH! I've had a really frustrating evening/morning. My 20 gallon tank turned into a mystery deadzone. Last night, I found one of my bettas dead - my red one - looking completely washed out - like a ghost - no signs of illness, no bitemarks - just dead.
I did a dip test - and had zero nitrates/nitrites - but the PH and GH levels were skyrocketed???
WHat would cause this? For the first month and a half, the PH was testing at 7.2- 7.4 and the GH was always 3 - 4 drops.
The only change that has occured on the tank is that I began a week ago to supplimental feed with lettuce for my otos. And, On Sunday, I switched to cucumber (I went shopping). And, I added the new Echeim canister filter to the tank on Saturday (which has given significant more water circulation - so I was able to shut off the koralia powerhead).
I decided to do a 25% water change (I needed to top off the tank anyway so it seemed prudent to change some) - and this morning, I found another dead betta! -
ARGH! and looking at the other 4 - the colored ones, at least - they all have stress stripes.
So I did the API tests this morning and the PH level is now back down to 7.4. No ammonia. no nitrites. no nitrates. - zilch.
The cories and otos are munching away. Although I removed the cucumber that was 24 hours old - this morning, and decided it was best not to replace it until I figure out what's wrong with my tank. There's sufficient algae still that's regrowing on the glass that the otos won't starve today.
I had to set up emergency homes for the remaining 4 betta girls though. I just don't trust the tank with them, especially seeing how stressed they're looking. I have 2 - 2 gallon 'Q' bowls - and I took the smallest 2 babies and they're in a breeder's net hanging in the 30 gallon tank with a ton of floaters around the outside of the net to protect them from too much pestering...
My King Betta male in that tank - His reaction thus far is to do a LOT of swimming around the tank and checking them out though... and some flairing... Definitely this is not an ideal fix.
When I woke up this morning, I had not intended to turn that tank into a sorority... now, I don't know what other options I will have.
How do I figure out what's wrong with my 20 gallon, and how the hell do I fix it???

[ScentedLove]

Idk but I hope someone will help you and good luck and sorry about your girls ;(

[RoseyD]

Well, someone posted on the plant forum that I could have media problems with the new filter if I didn't rinse the media enough.

So, I'm glad I removed the bettas before I left for work this morning, let's hope that the otos and cories remain healthy until I can get home and figure out how to clean the new filter without flooding my apartment...

If this is the problem - then it'll be an easy fix - but I did rinse the matrix that came with the filter when I set it up on Saturday - so I wonder how I could have screwed up on this...

[dramaqueen]

I think you're supposed to rinse the filter media with tank water, not new water. Someone can correct me if I'm wrong.

[RoseyD]

OH! ... I thought that was only after the media was 'bacteria filled' because of possible chlorine in tap water killing bacteria.

So, you rinse new media with tank water too? I wish it had said this in the directions...

[sumsum]

If the filter has strong suction it could have sucked the fish up to it and killed them when this happens it usually releases the fish and it does not appear to be harmed but it is dead. This happened to two of the gold fish my teacher had in the classroom. Sorry about your poor little fishies

[dramaqueen]

I didn't know it was a new filter so I don't know.

[RoseyD]

It doesn't have strong suction, persay - it's the echeim 2232 - for 35ga - canister filter - and I put the intake hose behind a ornament that is mostly used by the otos/cories without them having difficulty in being in front of it... As well, I use the ornament to hold the vegetable 'down' for the otos to munch on. And the veggie isn't sucked into that intake valve.

the current comes from the return hose that is pretty strong that if the fish swims directly under it, or if the floater plant gets caught in it - it's immediately pushed toward the 'ground'. This spacial effect is only to a quarter (or less) of the 20 gallon tank, and I've watched all the fish swim through it - although, the cories aren't nearly as zippy and usually make the extra effort to go around that 'spot' of the tank to get to the other side.

[neenjar]

As far as rinsing new media, it does not need to be tank water, just dechlorinated. I have been doing it that way for years.

[RoseyD]

Could the adding of a filter 'raise' my PH and GH levels?

I'm still running the duetto on the tank figuring that would be the only way to keep the tank cycled. I have no intention to remove the original filter for at least another month...