Check your hydromiter, put it in clean water and it should read zero.
If you filled it to 23 liters you should have got abolut 1.045 or so. I used to get about 1.040-1.042 with kits.
only other thing i can think off is that you sisnt disolve all the ingredients properly and what you tested was weaker.
I always disolved the kit in about 8 to 10 liters of hot water in a pot. I would heat uo the water on the stove to about 70 odd degrees and empty in the tin. (It helps if you stand the tin in hot water for 15 min before opening it to make it nice and runny for tipping out)
I then stired in the kit till it is all disolved and then add all the other ingredients and stir them in as well.
you now have about 12 liters of hot syrup.
Put this pot in the laundry sink or anywhere it will fit and fill around it with cold water to cool it. try not to get anything in the pot to avoid infection.
change the water a few times to cool it down, even add ice.
once its down to 20 deg, tip it in the firmenter and top it up with cold water from the tap.
stir it really well making sure you mix in lots of air to help the yeast along, it needs to breath too.
add your yeast to the wort when and ONLY when it is at about this 20 or so degree mark and gently stir in.
seal her up and firment as normal.
When i started i was tipping the tin in the firmenter and adding a couple of liters of boiling water to the firmenter to try and disolve all the ingredients but i found the water would saturate with sugars and not all of it would disolve, then when you top it up with cold water, half the tin of goo stays like goo on the bottom of the firmenter. you then get readings like 1.025 and 1.030 and think "shit" whats wrong.
the yeast and water will disolve it all and eat it up and it will be fine or you can bottle it and give it to the designated driver if itturns out to be a 3% beer
hope this helps
cheers
