SellFishes

6 comments

S ShrimpLord Oct 10, 2026 · 1:53 PM

Topping off with tap is your answer. Evaporation leaves the minerals behind, so TDS climbs every time you add tap. Top off with RO or distilled and only use remineralized water for actual changes.

PP Planted Pete Oct 10, 2026 · 1:55 PM

Yep, same thing happened in my low tech tank. Switched to RO top off and it stayed flat within a few points.

RF Riverina Fish Co. Oct 10, 2026 · 2:11 PM

ah that makes sense, I've been topping off with the same tap I use for changes. grabbing a jug of RO tonight. is distilled from the grocery store fine or does it need remineralizing for top off too?

S ShrimpLord Oct 10, 2026 · 2:15 PM

Distilled is fine for top off, you're only replacing evaporated water so nothing needs adding back. Remineralize only the water that goes in at a change.

RF Riverina Fish Co. Oct 10, 2026 · 2:42 PM

perfect, grabbed a gallon of distilled this morning. will report back on the TDS after a week of topping off with it.

S ShrimpLord Oct 10, 2026 · 2:47 PM

Good. Check TDS right after a change and again on day five, flat within 5 to 10 points means the top off was the culprit.

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