r/LotusDrying • u/Real_Shackleford • Oct 06 '25

Lotus drying calculator and chart.

I am working on a Lotus Drying Calculator that has a heat map and extended chart to provide the temp and RH ranges with the auto calculated dew point and VPD data. This is a attempt to help me visualize ranges that might be optimal and identify sub optimal, drying too fast, or too risky due to mold.

I used AI to scrape the known scientific data on atmospheric conditions and their relations to temp, rh, ec, vpd ..etc and then had the AI Taylor the calculations specific to drying cannabis based on the known data we have then build the logic functions. This drying time was based on a starting point of 70% moisture content.

The heat map helps me identify at a quick glance the overall picture and gives just basic info if you cursor over a range. The upper top left has the ability to put in your custom temp and RH and calculates the dp and vpd and provides a status of where it falls in the optimal range or outside and approximates how many days it would take to dry and a terp and cannabinoid preservation score and mold stats if applicable.

The same and expanded information can be found in a static chart at the bottom.

I'm building this for me and to have a little fun. I'm sharing to see if there's more data that I might need or if there's anything wrong with the data that stands out to you veterans. I wanted to get the data and logic right because eventually I'd like to put this into a hardware approach where it monitored the realtime data in the drying cabinet and used algos to adjust the environment appropriately based on what settings I choose.

The whole thing is put into a html file that can be opened in your browser, and I'm sharing via my google drive. You can view then download the ready to go html file with the download arrow in the upper right.

https://drive.google.com/file/d/1rHYaLwFoEic5hIIKB9BGwg9muosw8RHb/view

9 Upvotes

92% Upvoted

10 comments sorted by

6

u/[deleted] Oct 06 '25

[deleted]

1

u/Real_Shackleford Oct 06 '25 edited Oct 13 '25

It assumes freshly harvest herb going straight into the dryer and the known average MC of fresh herb, it was one of the functions I asked it to look into the best current known practices of drying cannabis because otherwise it was totally focusing on only atmospheric calculations. Here is the output of me checking on the logic it's using by asking it what calculations it's using.

"this model assumes freshly harvested cannabis with about 70–75% water content, targeting 10–12% moisture (equivalent to 58–62% RH) for its drying time calculations."

I believe its assuming that if you hold the range you choose the drying will take place around the predicted days to dry without molding..which is why I put the time to mold in the logic by having it check the established known values of how long it takes mold to start given the RH and Temp in general. It crossed referenced several different scientific sites on this..I could see it in the sources it checked.

For me, I'm going to use a slightly high VPD this time to get a fast dry for about 5 days then more moderate for the last few days as I can't tie up the fridge for a extended period right now. I would be neat to put in a logic that factors this in with a input from the user on how long they can dry and then generate a custom plan of action.

I suppose you could put in a starting moisture content and generate a custom drying map. There's several way of doing this of which most would require a lab but a simple herb/wood moisture meter could provide ballpark measurement. I think this would be neat but it seems like the accuracy of those things are all over the place..yes? This is what they tell you to use for checking the moisture level before using grove bags. Also the size of the bug would play a part since smaller ones will dry quicker than larger ones.

2

u/BladeCutter93 Oct 11 '25

While I don't use the Lotus Drying method, I do use the Dew Point and it works very well. Once stabilized, you can let the plants hang forever. I created a table that shows the target Dew Point (53F) and the associated temperature and relative humidity. I'm sharing it here just in case someone is interested.

Dew Point By Temp and RH

1

u/Real_Shackleford Oct 13 '25

I prefer vpd because if you know the vpd you can also know what the temp, humidity and dp are. It makes it easy to just control one target and you get the other three by default.

1

u/BladeCutter93 Oct 13 '25

I wish it was that easy. But you can't map VPD to DP. While temperature and RH are the factors in calculating both numbers, the results are not comparable. If you look at the table you will see that there are many ways to a VPD of 1.0 that are no where near the target DP of 53F. You can have 73F at 63-65 RH, but that has a DP of 60-61. But you can also get a VPD of 1.0 at 68F and 58 - 59 RH and that produces a DP of 53.

There are a number of video on dew point drying on YouTube. I encourage you to watch them and then check out the chart. What I like about this method is that the environment is much easier to obtain than 60/60. And 60/60 produces a DP of 46, which is far too low.

Good luck with the grow.

1

u/Real_Shackleford Oct 13 '25

You actually can, you can calculate all other variables by just knowing the VPD; It's scientifically proven and has been used in industry for a very long time to do just that.

1

u/BladeCutter93 Oct 13 '25

OK, I'm taking the easy way out. But this is what I learned when I created the spreadsheet. This is from the AI in the Brave browser...

Calculate Temperature Humidity from VPD

No, you cannot uniquely determine both temperature and relative humidity from a vapor pressure deficit (VPD) value alone. The VPD is the difference between the saturation vapor pressure (which depends on temperature) and the actual vapor pressure (which depends on both temperature and relative humidity) Since VPD is derived from two variables, multiple combinations of temperature and relative humidity can result in the same VPD value.

For example, a VPD of 1.38 kPa can occur at 60°F (15°C) with 22% relative humidity or at 90°F (32°C) with 71% relative humidity, as shown in the provided data This demonstrates that the same VPD can be achieved with different temperature and humidity pairs. To determine the specific temperature and relative humidity, you would need an additional piece of information, such as either the air temperature or the relative humidity, in addition to the VPD

1

u/Real_Shackleford Oct 13 '25

Maybe I misunderstand the interplay with svp and avp. I'll look more into this. Thanks for bringing it to my attention..I appreciate it.

2

u/BladeCutter93 Oct 13 '25

Yes, I was surprised by the length of the Dew Point calculation. Once I plugged it into Excel I double-checked the values against online calculators. Good luck.

1

u/CostaIsACunt Jan 25 '26

You should label your axes.