Mystery Guppy Death

[Leeandoona]

Help! I’ve been keeping fish for years. Had a break from the hobby for a few years when we moved home. Set up a new aquarium details below. It’s cycled for 3 weeks and then added a group of male and female guppies from local store. All was well for about three days and the we began observing the guppies all swimming at the top of the water column. Checked water conditions and all was within range for a recent setup. Then each day a guppy has died. During this time they have also bread and we have some fry. The fry appear healthy but each morning we’ve found another guppy dead.
The dead guppies show no sign of damage, no fin rot, no strange colouring or signs of fungus. Their gills are Normal in appearance and they are not thin or distended. They die at night.
I’ve carried out 25% water change. Still losing one a day. Only have two females left and the two fry that were born in the aquarium.
Setup:
150 ltr
Overhead trickle filter powered by a JAD 12.5w 740L/H submersible pump. Trickle filter is sponge, balls and ceramic pieces with carbon pockets.
Additionally I have a EF-150 external canister filter with 3 grades of biofoam.
we also have an air curtain/stone.
Substrate is fine gravel which was pre washed in clean water plus plant friendly bio gravel. I have self sown aquatic plants, some shop bought elodea and an aquatic Lilly.
Tank is lit for 9 hours a day via a single LED tube light.
Temp is 27c
PH is 8.0 GH 180 KH 160
NO2 0.5 NO3. Between 0 and under 20.
In desperation I bought a liquid tank water additive which should zero NO2 and NO3 plus acts as a de chlorinate and as a ph Buffer. The down side of adding this is that it will then give a false positive reading on NO2 and NO3 so I don’t want to add this until I know what’s going wrong.
I’ve never had a problem like this in decades of fish keeping so I’m mystified.
Any ideas?

 

[Essjay]

Can I ask a few questions, please?

Checked water conditions and all was within range for a recent setup.

What are the numbers for ammonia and nitrite? No matter how long the tank has been set upm these should always be zero. If they are above zero, water changes need to be done to get them down.

It’s cycled for 3 weeks

How did you cycle the tank? A cycled tank should have zero ammonia and nitrite.

In desperation I bought a liquid tank water additive which should zero NO2 and NO3

What is the additive? Things like Seachem Prime only detoxify ammonia and nitrite for 24 to 36 hours so a water change must be done if ammonia and/or nitrite is above zero before they un-detoxify.

 

[Leeandoona]

Can I ask a few questions, please?


What are the numbers for ammonia and nitrite? No matter how long the tank has been set upm these should always be zero. If they are above zero, water changes need to be done to get them down.


How did you cycle the tank? A cycled tank should have zero ammonia and nitrite.


What is the additive? Things like Seachem Prime only detoxify ammonia and nitrite for 24 to 36 hours so a water change must be done if ammonia and/or nitrite is above zero before they un-detoxify.

The NO2 (Nitrite) is zero ppm and that NO3 (Nitrate) is zero to 20 ppm which is a nominal reading of zero too. Guppies usually don’t have any problems with Nitrate up to 30ppm anyway. So it’s not that.
The water treatment is ‘Natural Rapport’ Also in 1 water conditioner. Claims it lasts 2 weeks. I do fortnightly water changes of 25%. Tap water stood in bucket is 2 weeks old and also tests zero for nitrate nitrite and Chlorine. The tank was cycled using boiled and cooled tap water, the filters were all. Brand news so added plants and snails first. Tank then set up and left like this for 3 weeks before water tested zero chlorine, zero nitrate amd nitrite. PH like I say is a little high at 8 but nothing excessive.

 

[Essjay]

What's the ammonia level?


I can't comment on that product as it doesn't say what's in it, I'm afraid; except to say it's got more in it than I like - pH buffer, electrolytes and some thing to promote the slime coat.