diff --git a/code/controllers/subsystem/air.dm b/code/controllers/subsystem/air.dm
index c79f9523c0..6f5d2ebe57 100644
--- a/code/controllers/subsystem/air.dm
+++ b/code/controllers/subsystem/air.dm
@@ -405,7 +405,7 @@ SUBSYSTEM_DEF(air)
 		eq_cooldown += (1-delay_threshold) * (cost_equalize / total_thread_time) * 2
 		if(eq_cooldown > 0.5)
 			equalize_enabled = FALSE
-		excited_group_pressure_goal = max(0,excited_group_pressure_goal_target * (1 - delay_threshold))
+		excited_group_pressure_goal = max(0,excited_group_pressure_goal_target * delay_threshold)
 
 
 /datum/controller/subsystem/air/proc/process_turfs(resumed = 0)
diff --git a/code/modules/reagents/chemistry/machinery/chem_synthesizer.dm b/code/modules/reagents/chemistry/machinery/chem_synthesizer.dm
index 489f9dd179..ae87d7714c 100644
--- a/code/modules/reagents/chemistry/machinery/chem_synthesizer.dm
+++ b/code/modules/reagents/chemistry/machinery/chem_synthesizer.dm
@@ -53,10 +53,10 @@
 				return
 			beaker = new /obj/item/reagent_containers/glass/beaker/bluespace(src)
 			visible_message("<span class='notice'>[src] dispenses a bluespace beaker.</span>")
-		if("amount")
-			var/input = text2num(params["amount"])
+		if("synth_amount")
+			var/input = text2num(params["synth_amount"])
 			if(input)
-				amount = input
+				amount = max(input, 0)
 	update_icon()
 
 /obj/machinery/chem_dispenser/chem_synthesizer/proc/find_reagent(input)
diff --git a/html/changelogs/AutoChangeLog-pr-15420.yml b/html/changelogs/AutoChangeLog-pr-15420.yml
new file mode 100644
index 0000000000..e97082f7ca
--- /dev/null
+++ b/html/changelogs/AutoChangeLog-pr-15420.yml
@@ -0,0 +1,4 @@
+author: "Putnam3145"
+delete-after: True
+changes: 
+  - bugfix: "Atmos group processing heuristic no longer does opposite of intent"
diff --git a/tgui/packages/tgui/interfaces/ChemDebugSynthesizer.js b/tgui/packages/tgui/interfaces/ChemDebugSynthesizer.js
index 0e073ba885..b82c793703 100644
--- a/tgui/packages/tgui/interfaces/ChemDebugSynthesizer.js
+++ b/tgui/packages/tgui/interfaces/ChemDebugSynthesizer.js
@@ -33,8 +33,8 @@ export const ChemDebugSynthesizer = (props, context) => {
                 maxValue={beakerMaxVolume}
                 step={1}
                 stepPixelSize={2}
-                onChange={(e, value) => act('amount', {
-                  amount: value,
+                onChange={(e, value) => act('synth_amount', {
+                  synth_amount: value,
                 })} />
               <Button
                 icon="plus"