Entire Batch Of Convict Fry Dead!

[fishlette]

ok, so i have a 30gallon cube with my breeding pair of convicts in it. the tank was new when they were put in but was set up with mature gravel, a mature filter and ornaments from a mature tank. i did small water changes every day and kept an eye on the stats and so far there has been no probs. 5 days ago the eggs hatched. i left the water for a couple of days and then tested it yesterday before doing a change. the stats were ammonia (not exact...showed signs of slight slight green to the water but basically nothing that a water change wouldnt fix) nitrites were the same and nitrates 20. i did a test about 10 hours later before i went to bed and the stats were all good; ammonia 0, nitrites 0 and nitrates 10. oh yeah and seeing as im having a prob with algae in that tank due to the absence of snails and BN i added some algae clear which after reading the bottle, didnt say anything about it affecting fry etc

i also changed the filter yesterday. i did have a 1200lph power head in the tank but the current was too much for the fry so i took it out, put it in my african tank and took the 700lph internal filter from the african tank and put it in the convict tank. i also added a new 400lph internal with some mature media from another tank.

this morning i have come out and not only is the tank covered in algae, all the fry are dead and the parents are gasping at the surface. i also have an air stone running in the tank.

i just cant believe the amount of algae that has grown overnight especially with the algae clear in it. there is also like a white build up on the heater stem. it kinda looks like the build up you get when salt is in the water and it accumulates on the dry areas. all plants, gravel, ornaments, filters etc are covered with this stuff in some form. the tank is near a window but doesnt get any direct sunlight as the window is shaded by trees and the veranda.

does anyone have any ideas i dont want to lose the parents as well

 

[vinylman]

What do you mean by ''changed the filter'' ?.

 

[fishlette]

What do you mean by ''changed the filter'' ?.

exactly what i said. i took the powerhead out and swapped it for a filter from my african tank plus added a new one with mature media from another tank

i know well enough about adding a new filter and starting a new cycle etc anyhoo, stats are fine

 

[Tokis-Phoenix]

Sounds like your tank went through a mini cycle if it was showing ammonia or nitrites at one point, fry are very sensitive to these things.
Its likely that the algae killer you put in the tank killed off all the algae at the time, which then got sucked into the filter and quickly decomposed and basically overloaded the filter with ammonia from the process. But all the dead algae would have created a lot of nutrients in the water, perfect for fueling another algae bloom. Ultimately with algae its best to try and find the cause of the problem and deal with that rather than use chemicals as algae killing chemicals can sometimes mess up the water quality like this and even make the algae problem worse in the long run.

My main advice would be to start doing lots of small regular water changes to help remove the old chemicals from the water and help keep more stable nitrates at low levels (which will help prevent algae growing as much), i would advise doing a 50-60% water change with dechlorinator right now, followed by lots of small and regular water changes over the next couple of weeks.
Does the tank have any live healthy plants in it?

 

[fishlette]

Sounds like your tank went through a mini cycle if it was showing ammonia or nitrites at one point, fry are very sensitive to these things.
Its likely that the algae killer you put in the tank killed off all the algae at the time, which then got sucked into the filter and quickly decomposed and basically overloaded the filter with ammonia from the process. But all the dead algae would have created a lot of nutrients in the water, perfect for fueling another algae bloom. Ultimately with algae its best to try and find the cause of the problem and deal with that rather than use chemicals as algae killing chemicals can sometimes mess up the water quality like this and even make the algae problem worse in the long run.

My main advice would be to start doing lots of small regular water changes to help remove the old chemicals from the water and help keep more stable nitrates at low levels (which will help prevent algae growing as much), i would advise doing a 50-60% water change with dechlorinator right now, followed by lots of small and regular water changes over the next couple of weeks.
Does the tank have any live healthy plants in it?

im not sure whats causing the algae. i assumed it was because its a new tank and there is nothing like BN's or snails in there. i wouldnt normally use chemicals for it as i have snails and BN's everywhere. i have since put a big snail in there but can i put a BN as well or would that be pushing the bounds of the convict friendship??

i have done that water change you said about. i have some live plants in there; anubias, eloadea, dwarf rush and dwarf pongo.

 

[fishlette]

UPDATE - Done water changes the last couple of days and the water is testing better now and the fish are much more active again. the female is even starting to colour up again already

i took everything in there out and washed it all and put it back in. i asked in my last post if i could have a BN in there and i have had no reply and seeing as this morning there is already algae growing, i put a BN in there. im sitting right next to the tank so i can see if anything happens but i think they are having second thoughts about harassing her as one of them 'sniffed' a little too close before and nearly got jabbed with her spikey things. so far all looks ok but can someone tell me for sure whether or not this would work long term

my next question is, if i cant keep the BN in there long term, how do you control algae in a tank???