Reef Tank RO/DI Water Guide: Why Tap Water Hurts Your Reef
If there's one upgrade that quietly fixes a surprising number of reef tank problems, it's switching to RO/DI water. At Tropical Treasures in Cheyenne, we can't count how many algae and coral issues we've traced straight back to tap water. Here's why your source water matters so much.
What's actually in tap water? 🚰
Even clean, drinkable tap water carries phosphate, nitrate, silicates, chlorine, chloramine, copper, and other minerals. Your body handles those fine, but in a closed reef they feed algae, stress corals, and throw off your carefully dialed-in parameters.
How RO/DI water works 💧
An RO/DI unit pushes water through a sediment filter, carbon block, reverse-osmosis membrane, and a deionization resin. The result is near-zero TDS (total dissolved solids) water — a blank slate you then mix salt into, so you control exactly what goes in your tank.
Why it matters for your reef 🐠
Starting with pure water means no surprise nutrients fueling algae, no heavy metals harming inverts, and consistent, repeatable water chemistry every time you mix salt or top off. It's the foundation everything else in your reef is built on.
Getting RO/DI water 🔧
You can buy your own RO/DI unit, which pays for itself over time, or pick up fresh RO/DI water by the jug. We sell RO/DI water right here at Tropical Treasures in Cheyenne — just bring a clean container. Browse our water and filtration supplies or call 307-369-1118 to ask what's in stock.
Do you really need it? 🤔
For a coral reef tank, yes — it's one of the best investments you can make. For a hardy fish-only setup you may get by with treated tap water, but you'll likely fight more algae. A cheap TDS meter tells you exactly what your water is bringing in.
The bottom line ✅
RO/DI water gives you a clean, consistent starting point that prevents algae, protects corals, and keeps your parameters stable. It's the easiest way to stop problems before they start. Need RO/DI water or a unit of your own? Stop by Tropical Treasures in Cheyenne or call 307-369-1118, and find more reef tips on The Tank Buddy Blog.