Stalled Ferment using Lowan's Instant Dried Baker's Yeast

[firrenzi]

TL;DR Mash is stalling at 1.025 from 1.065, don't know why

Hi Everyone,

Long time reader, first time writer.

I am wondering if someone can aid me in a brewing quandary. My SG starts off at about 1.06 to about 1.07 and I can't seem to get the SG down to less than 1.025. This has happened on the last 3 washes and I am wondering if the yeast I have doesn't like more than 5% alcohol.

Requested a spec sheet from the manufacturer but that wasn't really any help

These are the specs I start out with:

Sugar source is sucrose ( I have dextrose but haven't tried it with it)
SG: 1.07
Capacity: 25L
Recipe: Birdwatchers' TPW with variations (approx 150g of yeast
Yeast: Lowan's instant dried (approx 150g)
PH: approx 5 (citric acid)
Nutrients: DAP & 190g of condensed Tomato Paste
Sterilised using starsan
Pitch temp 28C
Brewing temp maintained at 33 C +/- 1 degree
Sugar fully dissolved with aquarium pump and temp brought up to 33 with two 50W aquarium heaters in approx 4 hours.


Temperature fluctuation overall is minimal

Process:

Activate yeast for 1/2 Hr in approx 2L of water with about 50g of sugar before pitching into wort.
Continue to run pump for another 4 hours after pitching
Leave lid off for approx 24 hours and then seal with airlock

Approximately 6-8 days later activity slows and there is very little change.

Possible variables:
*Yeast
Crappy yeast just doesn't like alcohol specs, but based on measurements it's stalling out at approx 6%. Pitch temperature is ok, perhaps temperature needs to come down as AbV comes up?
Should I leave yeast in starter longer?
Not enough yeast? I usually overpitch with the dried stuff anyway
Get fresh Baker's yeast


*Sanitation
Common mistake so I am fairly careful

*Nutrition:
Pretty well covered

*What I've tried so far to remedy it:
Pitching more yeast as a last ditch effort (doesn't usually work obviously)

*Sugar
Invert the sugar perhaps?

I don't know, I've "read and read till my eyes have bled" and all i can see so far is that I am getting the same result (SG of approx 1.025 and no further) and not able to get any joy.

My only two things that I can think of at this point would be invert the sugar, or get fresh baker's yeast or maybe even champagne yeast

Also wanted to thank everyone for their input on this forum. I have learnt and improved more than I could possibly imagine by so much valuable input and reading as much as possible. So once again Thank you.

For those new to this: read and read 'till your eyes bleed!

UPDATE

29/12 Pitching another 60 grams approx has produced some activity in the last hour