# Ph Rate of change formula **URL:** \ **Category:** Hydroponics\ **Created:** [December 15, 2019, 2:46pm UTC](https://ilgmforum.com/t/ph-rate-of-change-formula/38117 "2019-12-15T14:46:49Z")\ **Posts on this page:** 1\ **Showing post:** 20
**Author:** ![anon4427090](https://avatars.discourse-cdn.com/v4/letter/a/a9adbd/32.png) [@anon4427090](https://ilgmforum.com/u/anon4427090)\ **Post date:** [February 25, 2021, 11:29am UTC](https://ilgmforum.com/t/ph-rate-of-change-formula/38117/20 "2021-02-25T11:29:51Z")
Found it… one of the nerdiest math things i have attempted…not particularly sure if i even got it right but it is acting about how i expected > [@0\_o Nanashi's first grow (with pics)](https://ilgmforum.com/t/0-o-nanashis-first-grow-with-pics/60875/136): > > That is an excellent question for me to look in to. I did this with 2 spare junk fridges and the intention to change them out if i need to ( im just pushing for a single set of clones so a few weeks of life is plenty) But i did find myself playing with the idea of tube lengths and the rate of btu loss of the res itself and you asking is exactly what will make me check (its literally the reason im here) sooooo here we go. 0\_o 8.33 BTU A British Thermal Unit (BTU) is a measurement of heat ene… --- _[View the full topic](https://ilgmforum.com/t/ph-rate-of-change-formula/38117)._