APEX RF-1050 Alkaline Filter Cartridge
✅ PROS
- Adds beneficial minerals (calcium, magnesium, potassium) back into water after RO filtration, improving taste and pH
- Universal 10-inch standard size fits virtually any standard RO system or whole-house housing — no proprietary locking mechanism
- Delivers noticeable pH boost from ~6.5 to 8.5-9.5 at 1 GPM flow rate, verified by multiple reviewers with test strips
❌ CONS
- No built-in shutoff valve or bypass — water continues flowing through spent media, so you must track replacement by date, not taste
- Initial flush required (5-10 gallons) or you'll get black carbon dust in your first glasses of water
- Not a standalone filter — must be paired with an RO system or carbon filter upstream; doesn't remove contaminants on its own
The Verdict
APEX RF-1050 Alkaline Filter Cartridge Review: The Right Way to Fix Flat RO Water
If you’ve got a reverse osmosis system, you know the problem: the water’s clean, but it tastes flat. Lifeless. Like drinking rain. The APEX RF-1050 is designed to fix exactly that — by adding minerals back after the RO membrane strips them out.
Here’s the honest breakdown.
What You Actually Get
The RF-1050 is a standard 10-inch cartridge (9.75" x 2.5" to be exact) filled with a proprietary blend of calcium, magnesium, potassium, and other trace minerals. It’s designed to be the last stage in an RO system — the water passes through the membrane, then through this cartridge, and comes out with a higher pH and better taste.
It’s a universal fit. If your RO system uses standard 10-inch housings — which most do — this snaps right in. No adapters, no proprietary locking rings, no headache.
Real-World Performance
Here’s what actually matters: does it work?
Based on the 229 ratings at 4.6/5, yes — with some nuance. One reviewer put it plainly: “Took my water from 6.5 pH to 8.5. You can feel the difference in how the water tastes.” Another noted: “The minerals aren’t just for taste — I could actually tell my body felt more hydrated.”
The media is dense. At 1 GPM flow rate, the contact time is enough to actually raise pH — which is the single biggest failure point for cheap alkaline cartridges. This one does what it claims.
The taste improvement is the headline. RO water goes from “flat” to “crisp” — that slight sweetness you get from natural spring water. If you’re a water snob, you’ll notice it immediately.
Where It Falls Short
Let’s be honest about the gaps.
No shutoff valve. This cartridge doesn’t stop water flow when spent. You need to track replacement by calendar (typically every 6-12 months or 1,500 gallons), not by taste. If you forget, you’re drinking unfiltered RO water without realizing it.
Initial flush is mandatory. The first 5-10 gallons will have black carbon dust. If you skip the flush, your first glass looks like you’re drinking from a mud puddle. Read the instructions.
It’s not a standalone filter. This adds minerals — it doesn’t remove contaminants. You need an RO membrane or carbon filter upstream for that. If you’re buying this as your only filter, you’re doing it wrong.
Who Should Buy This
Buy it if:
- You have an RO system and hate the flat taste
- You want to raise your water’s alkalinity without buying expensive bottled alkaline water
- You’re replacing a spent alkaline cartridge and want a solid, consistent performer
Skip it if:
- You have municipal water that’s already well-balanced (you won’t notice as much benefit)
- You need a complete filtration solution — this is a finishing touch, not a foundation
- You’re prone to forgetting maintenance schedules (no shutoff = no reminder)
FAQ
Q: How often should I replace the RF-1050? A: Every 6-12 months or 1,500 gallons, whichever comes first. If you’ve got a family of four, plan on 6-month replacements. Mark it on your calendar — there’s no indicator.
Q: Will this fit my system? A: If your RO system uses standard 10-inch x 2.5-inch cartridges — which covers 95% of residential systems — yes. Check your current cartridge dimensions before ordering.
Q: Does it actually make water more alkaline? A: Yes. Multiple reviewers measured pH increases from 6.5 to 8.5-9.5 with test strips. It’s not a gimmick — the mineral media is dense enough to do the job at normal flow rates.
The Verdict
Rating: 4.6/5
The APEX RF-1050 does exactly what it promises: fixes the flat taste of RO water and adds beneficial minerals back. It’s well-built, universally compatible, and delivers measurable results. The lack of a shutoff valve and the required initial flush are minor annoyances, not dealbreakers.
Buy it if you want your RO water to taste like actual water again. Skip it if you’re looking for a complete filtration system — this is a finishing cartridge, not a primary filter.
For the price of a few bottles of fancy alkaline water, you’ll get months of better-tasting, mineral-rich water for your whole family. That’s a solid trade.
Where to Buy
We earn a small commission at no extra cost to you — this helps fund more honest reviews.
Last updated: 2026-08-06. Ratings and prices current as of review date. Verify on Amazon before purchasing.