I am not the OP, but I’d love to hear the details on setting up AWC this way with Hydros!
Hydros Start AWC + ATO Setup (Cost Breakdown & Walkthrough)
Before getting into the setup, here’s a complete cost breakdown of the equipment you can use with the Hydros start for a Hydros-based Automatic Water Change (AWC) and ATO system. I personally use the control X4 bundle and XP8 bundle, but both work.
Links to all items (by name) are on page one of my build thread. All of my Hydros settings with screenshots and a more detailed explanation are in the middle of page four of my build thread.
Equipment & Pricing
Hydros Start – Main controller – $329.99
Hydros Triple Water Level Sensor – ATO + AWC control – $46.19
Hydros Water Level Sensor – Additional level sensing – $46.19
Hydros Dosing Pump – AWC drain pump (peristaltic) – $69.29
MostAqua ATO/AWC Pump – AWC fill pump – $13.99
MostAqua ATO/AWC Pump – ATO pump – $13.99
K-Mains Plug Adapter – Adapter for AWC fill pump – $10.03
K-Mains Plug Adapter – Adapter for ATO pump – $10.03
Total system cost: $539.70 (prices reflect what I paid) links on first page of build thread.
Controller overview: The Hydros Start gives you 4 sense ports, 2 drive ports, 4 controllable outlets, and a command bus to add additional controllers or an XP8 if more outlets are needed.
How I’m using the ports: In this setup I’m using 2 sense ports, 1 controllable outlet (possibly 2 depending on pump choice), and 1 drive port. The drive port is used for the AWC drain pump. I run a Hydros dosing pump here because it is peristaltic and prevents back siphon. You can run the ATO off the second drive port if you want, but I chose to run my ATO pump on a controllable outlet instead.
ATO pump choice: For the ATO I purchased a second MostAqua pump. It runs off a controllable outlet and shares the same sense port logic as the AWC. These pumps are inexpensive, have sufficient head height, and are the same pump Hydros uses for their ATOs, just without the drive-port connector. Both pumps require a K-Mains plug adapter since the output isn’t a standard wall plug.
Sense ports and water level logic: I’m using Hydros water level sensors including a triple water level sensor. This single sensor handles both ATO and AWC logic.
The upper sensor has two sense locations. When AWC is OFF, these two points function as the ATO control. The upper point is ATO OFF and the lower point is ATO ON. When AWC is ON, the lower of the two upper points becomes the AWC drain stop and the upper point becomes the AWC fill stop.
The lowest sensor on the triple sensor is always submerged and defines the maximum drain depth. This determines how much water can be exchanged. It’s important not to set this too low or you risk exposing heaters or other equipment.
How the AWC works: The drain dosing pump removes water until the lower sense point is reached. The fill pump then adds fresh saltwater until the upper sense point is triggered. I keep two buckets below the tank, one for fresh saltwater and one for drain water. I prefer running multiple smaller water changes over several hours instead of one large change for better stability.
Safety features: Hydros has excellent safeguards. You can set maximum run times for both ATO and AWC, it protects against sensor failure or dirty sensors, logs all on/off activity in the app, and sends alerts and emails if there’s ever an issue. Make sure “Run Past Max Time” is disabled or the pump will continue running after hitting the max limit.
Water change volume: For my tank, the Hydros dosing pump runs about 5 minutes per cycle, 5 times per day, which comes out to roughly 2.3 gallons per week. For larger tanks you may want a faster peristaltic or dosing pump, but sticking with peristaltic pumps is key to preventing back siphon.
Final notes: Page one of my build thread has links to every item by name. The middle of page four has all my Hydros settings, screenshots, and a more detailed explanation of how everything is configured. If anyone has questions or wants help adapting this setup, feel free to ask.
