chemi pure can't be regenerated, but it doesn't do the same thing as purigen. I use chemipure elite and purigen in my canister on my mbuna tank. Chemi pure elite removes silicates, phosphates, dissolved organics, heavy metals, phenols, supposedly helps maintain stable pH & eliminating osmotic shock (supposedly). Purigen has a high affinity for nitrogenous organics, helping to control ammonia, nitrate, & nitrite and "significantly raises redox" It does very well to polish water. I run both. If you had to pick one, I would go with purigen.