New tank - f8 both died within 3 days

[Tjforce12]

Hello,

Had a new 40 gallon tank for one month. Both f8s died within 3 days (not aggressive towards each other).

Started tank with Stability for new aquariums. 4 capfuls. Used water with dechlorinator. Black sand. Did not do water change but topped off with declorinated water 2x.

Readings after 2nd died.

A little less than 1 ppm amonia (i know thats high)
0 nitrite, 0 nitrates, 7.8 ph, 1.007-.008 salinity, 83 degrees.

Aquarium is aquatop all in one 40 gallon cube.

About a week before death, algae developed and i scraped the sides and cleaned off the ornaments.

1. WAS IT THE AMONIA alone?

2. Can i salvage set up, or do i need to completely drain and clean out filters, etc?

3. We had f8 for 3 years in a prior 20 gallon. At the time i used entire bottle of tetra safestart plus, this stability recommended much less. Is that a problem?

Any help would be appreciated as we are novices.

[Pufferpunk]

Sorry for your losses. I would do a 100% WC & start over.
I don't know much about Stability but have always had great results with Safestart. I suggest testing the system with 4ppm clear ammonia, to be sure it is gone within 24 hours. If not, keep adding daily until it does.

[TyeTye]

GSP and Figure 8 puffers are extremely hard to keep alive when you first get them. It took me 5 GSP to keep one alive. I have had Sandra for 5 months now, in a 75 gallon tank by herself. I would like to think she is living the best life, a GSP can have.

[Pufferpunk]

Not true at all. I never had a GSP or F8 die on me. Nor any other puffer. Unless it was old age. The tank MUST be properly cycled.