Will my platy die?

[PheonixKingZ]

The only thing I have to add, is definitely get the API master test kit.

Cloudy water usually indicates a bacteria bloom. Remove any uneaten food and/or dead/decaying plants.

Fish swimming across the tank very fast is normal for new fish, but should not be occurring on a day to day basis.

I see just from the pictures, you do indeed have a background on the tank? Is the tank near a window or place where there is a lot of activity?

 

[ElegantScents.co.uk]

The only thing I have to add, is definitely get the API master test kit.

Cloudy water usually indicates a bacteria bloom. Remove any uneaten food and/or dead/decaying plants.

Fish swimming across the tank very fast is normal for new fish, but should not be occurring on a day to day basis.

I see just from the pictures, you do indeed have a background on the tank? Is the tank near a window or place where there is a lot of activity?

It's in the corner of the room, not overly high traffic, apart from my children peeking at them.
If I could swap the children out for a short while, it would be very quiet and peaceful!

I got an ammonia test while waiting for my amazon master kit. Ammonia is still at 0. Nitrite and Nitrate at 0 too.
I did use a filter boost yesterday, could that have contributed to the bacteria bloom.
Is a bacteria bloom bad? Or is it the start of the tank cycling?

They're miles more settled now, the little platy has gone to the corner just a few times, but only for a few moments each time.
He's spending a lot more time in the plants with the tetras

I've also bought more top floating plants and will properly root and inspect the plants at Tonight's water change. I'm waiting until the toddler has gone to bed. He's slightly feral ‍

 

[AilyNC]

I feel you on feral toddler

 

[kwi]

It's only now my youngest is 4yo that I've decided we can safely have fish...........

 

[Ch4rlie]

I did use a filter boost yesterday, could that have contributed to the bacteria bloom.
Is a bacteria bloom bad? Or is it the start of the tank cycling?

Yes, that is likely, bacterial growth means bacteria bloom.

Bacterial bloom is a good sign that your tank is starting to cycle.

The bloom will go away of its own accord after a while so don’t worry about that for now.

Bit unsightly seeing the bloom but no harm at all.

 

[PheonixKingZ]

Yes, bacteria blooms are a good sign, for just staring the cycle.