Molasses/sugar wash ratios

[RūmHôk]

From all my reading here and other places I have jotted down some key points, which now seem more confusing.
Some clarification would be very appreciated.

Statements that have been made:

For every 1kg sugar, use 4L water.
For every 1kg molasses, use 5-6L water.

Question is if molasses contain only half as much fermentable sugar as sugar, is viscosity and possibly pH the reason for more water/kg?

Max molasses in wash should not exceed 16%
Max sugar in wash should not exceed 20%
Is this in volume/volume or as in the previous statement weight/volume?

I ask specifically because the thick heavy molasses I have weigh in at 35kg/25L and before I fill the first of two 1000L fermenting tanks, I'd like to be confident of the recipe
(I have tried several different recipes and have had random miscellaneous successes)

I see many recipes using various combinations of sugar and molasses and have been trying to find a good balanced average or at least some kind of correlation and have come up with this:

Molasses: 20% of total wash volume (v/v) added to hot dunder from run just completed.
Sugar: 5% of total wash volume (kg/L)
Dunder: 15% of wash volume (up to 25% of water volume)
Baker's yeast @20g/kg sugar and 10g/kg molasses, started in 1-2L warm water + 1 crushed vitB complex pill and a few drops of warm mix from pot.
Also add 2-3L old yeast bed from previous ferment.
When I use this, I also add 15g Epsom salt + 15g Bicarbonatede of soda to 32L wash (which is split into two 20L buckets to ferment, 16L each leaving 20% space on top
The pH usually upwards of 4.6 no more than 5.2 and temp fluctuates from 32°C to 18°C St night, but all wrapped in blankets and space sheets to retain heat.
SG ranges 1.160-1.025
FG ranges 1.025-0.990
And this yeilds from 26-28L run from pot still and two thumpers, a volume of from 6-10L collected and 4-6L of 70-74% product.

Doing the backwards calculations, an incredible amount of tails + some heads and water to 15-25% ABV in the first thumper (6-12L) and heads + water to 30-40% in second thumper (4-8L) are turned into product 80-60% with wash calculating only around 4-7% ABV (1200-1800mls etoh)

Any comments advice guidance cautions pointers in the right direction will be very much appreciated.

Thanks.

[Saltbush Bill]

temp fluctuates from 32°C to 18°C St night, but all wrapped in blankets and space sheets to retain heat.

What is the temp of the wash while fermenting ? Air temps don't mean much. If the wash is started off to hot and is insulated immediately you could be damaging the yeast from to much heat. If started to cold it might never be getting warm enough to ferment well.
Try keeping you wash at a constant 34-36c and see what happens.
I dont use sugar and have never experienced PH issues with Rum so wont comment on those.

[RūmHôk]

Thanks Bill, appreciate the advice.
Being new(er) than most, I know the questions seem elementary - it's more a matter of learning to discern how much what has influence.
For a long time I was measuring carefully and trying to be 100% accurate with ratios, eventually learning that on 32L a few mls here and a couple grams there aren't as critical as 10°C and yeast activation.

I have not monitored with any accuracy the ferment temps; usually adding started yeast to wash when they're at the same temperature feeling by hand.
This takes place mostly at night so well below 30 and even down to 12°C that's why wrapping in blankets, 5 to 10 at a time on planks raised offtheconcrete floor and away from the walls, nicely covered. This I keep an eye on until action. It seems to stay consistently warm for the first very bubbly 24-48hrs dropping temp as activity subsides and stops after about 4 days.
I don't usually take it to the pot for a fortnight from beginning.

[v-child]

I've had very good and consistent results with:
13 gallons water
2 gallons food grade molly
13 lbs sugar
one Tbsp citric acid for ph
one Tbsp DAP
Lemon juice for sugar inversion

1/2 gallon of molly added to boiler during spirit run tends to bring the molly essence over.

The sugar content in molasses varies, so don't expect one person's results to be the same as yours. People seem to overthink and fiddle with their wash too much. Mix it and toss it in the bucket to ferment, wait until it's done and run it- strip runs then spirit run. Pretty drinkable the first day, better as it ages. I ferment at 72 to 75 degrees F, where it seems to be happy.

[RūmHôk]

Ok great! Thanks for the advice.
I'm tending more towards less sugar more molasses and of course dunder.
I run a double thumper and am playing with how much of who goes in where still.
What's amazing is how heads and tails and oils I put in, are coming out at around half the volume and pretty much same ABV. So half the non drinkables thrown in turn into drinkables.

One calculation still outstanding is working back from total distillate produced to how efficient the ferment was...if anybody gets what I'm trying to find out...?

[Trapped-in-Oz]

For a 9 litre wash:

molasses (unsulphured) - 1766 g (3 jars)
sugar (inverted with citric acid 8 g) - 1400 g
tomato paste - 120 g
Vegemite (40% less salt) - 6 g
Epsom salts - one fat finger pinch (about 1 g)
calcium carbonate (precipitated chalk) - 12 g
yeast GR-2 10 g
no DAP

Next, might try with only the molasses, inverted sugar and yeast.

[higgins]

I'm a newbie and have only done 2 rums so far, but I'm happy with the results.

The first was 50/50 by weight Golden Barrel blackstrap molasses and demerara sugar (11.5 lbs each) in 10 gallons water, with 5 tsp DAP, and 5 tsp DADY. OG 1.081, FG 1.005. 1 stripping run and 1 spirit run yielded 1 gallon at 125p. It is about 4 months on 'used' oak sticks and is coming along nicely.

I then bought a 30 gallon barrel for a fermenter, and the second one was scaled up to fit in that.

The second was 100% GB blackstrap molasses - 5 gallons in a 26 gallon wash, with 2 tbsp DAP, 2 tbsp Gypsum, and 4 tbsp DADY. OG 1.082, FG 1.015 (I was rather suprised that it finished this low being all molasses). 2 stripping runs and a spirit run yielded about 2 1/2 gallons (fairly wide cuts) at 125p. This one is only a month on oak and is already tasting better than the first - lots more flavor.

[Sporacle]

I use 5L food grade molasses, 2KG organic raw cane sugar, water to complete 25 litres in the fermenter, 1Tbsp safyeast C 70, ferment at 30C. SG is really high, but I've read that molasses will give funky readings. From what my limited newbie brain can figure I'm at about 13% abv. Haven't really checked the ph but seems to ferment out well. Just stripped and did a spirit run, made my cuts and time will tell.
If anyone new is reading this I tried to do my cuts by diluting to around 40%, got really confused tastes. Changed to about 25% and it really made it easier, not the way to do it im sure but worked for my palate. Make notes