Blog
How to Change Sand in a Pool Filter (Without Destroying the Laterals or a Vacuum)
Change pool filter sand every 3–5 years, and judge by symptoms rather than the calendar: backwashing needed more and more often, pool c...
How to Backwash a Pool Filter: All Six Valve Positions Explained (Sand & DE)
Backwashing reverses water flow through the filter to flush trapped debris out to waste, and the procedure is stop pump → valve to BACK...
What Is a HEPA Filter? (99.97% of What, at Which Size — and Why Your HVAC Probably Can’t Have One)
A HEPA filter is a defined media standard, not a brand or a style: any media that captures 99.97% of particles 0.3 microns and larger q...
Mold on Your Air Filter: What It Means, and When to Actually Worry
Mold on an HVAC filter usually means the filter got wet and stayed wet — replace it and fix the moisture, in that order — and in most c...
How to Clean a Washable HVAC Filter (And the Third Wash That Quietly Ruins It)
Cleaning a washable HVAC filter is a five-step, thirty-minute job: kill power, vacuum the face first, rinse at low water pressure with ...
Chlorine in Your Water: MRDL 4.0, Reading Your Free Report First & the THM Side-Story
For a quick reference on chlorine, see our chlorine entry.
Quick answer: Chlorine in municipal tap water is regulated as a disinfec...
Manganese in Your Water: 0.05 mg/L, the Black Stains & the 2021 Health Advisory You Should Know About
For a quick reference on manganese, see our manganese entry.
Quick answer: Manganese carries two numbers, and most pages blur them:...
Sulfur Smell in Your Water: the Cold/Hot Split Test That Might Cost You $15 Instead of $1,500
For a quick reference on sulfur smell, see our sulfur smell entry.
Quick answer: Rotten-egg smell is hydrogen sulfide (H2S) or sulf...
Arsenic in Your Water: 10 ppb, the As(III) Trap & the Full Removal Cost Sheet
For a quick reference on arsenic, see our arsenic entry.
Quick answer: Arsenic's federal limit is 10 ppb, and long-term exposure ab...
Bacteria in Your Water: HPC vs. the Dangerous Ones, UV Class A vs. B & the Honest Carbon Problem
For a quick reference on bacteria, see our bacteria entry.
Quick answer: "Bacteria in water" spans two very different findings — a ...