MPS for 250 gallons
| Dose | Grams | Ounces | Approx. measure |
|---|---|---|---|
| Weekly | 53 g | 1.9 oz | 2½ tbsp |
| Two doses | 106 g | 3.8 oz | ¼ cup |
| Three doses | 159 g | 5.6 oz | ½ cup |
How much non-chlorine shock for a 250 gallon hot tub
A 250 gallon hot tub takes 1.9 oz (53 g) of 45% non-chlorine shock per dose, about 2½ tbsp. Use it weekly and after heavy soaks. Many labels allow soaking about 15 minutes later. In a bromine tub, test bromine first: this full dose can read about 27 ppm from the bromide reserve, so the calculator sizes a smaller routine dose from your reading.
Run it with your numbers
Add
1.9oz
of Non-chlorine shock (MPS 45%)
53 gabout 2½ tbsp by volume
The routine label dose for 250 gal: once a week, and after a heavy soak.
- Side effects: TA −12 ppm.
- MPS reads as combined chlorine on DPD tests for about a day. Test CC the next morning.
- Run the jets with the lid open and wait at least 15 minutes (20 after pH decreaser) before anyone gets in.
- MPS shows up as combined chlorine on DPD tests for about a day.
- MPS burns off what soakers leave behind but does not sanitize. Keep chlorine in range as well.
- Leave the cover open for at least 15 minutes with the jets running.
Check the product label. Strengths vary by brand, so enter the % printed on yours. Add one chemical at a time, into the water, and never mix chemicals.
Save this test and get a reminder before your next soak.
Spa Calc for iPhoneComing soon to the App StoreAbout non-chlorine shock
MPS oxidizes the sweat, oils and lotions soakers leave behind, without adding chlorine. It does not sanitize, so keep chlorine or bromine in range too. In a bromine tub it also reactivates the bromide reserve.
MPS shows up as combined chlorine on DPD tests for about a day, so test combined chlorine the next morning. It slowly lowers alkalinity: check TA every week or two.
A 250 gallon tub
Inflatable tubs near this size include the Bestway Lay-Z-Spa Vegas AirJet (4–6 person) (247 gal) and the Coleman SaluSpa AirJet square, 114 jets (6 person) (222 gal). 250 gallons is typical of 2 to 4 person inflatable and small hard-shell tubs. With so little water, one soak moves the numbers a lot, so test before every use and dose in grams rather than scoops.
Questions
How much non-chlorine shock for a 250 gallon hot tub?
1.9 oz (53 g) of 45% MPS per dose.
How long after non-chlorine shock can I use the hot tub?
Many labels allow about 15 minutes with the jets running. Follow your product’s label and test sanitizer first. In a bromine tub, soak only once bromine reads 6 ppm or less.
Does MPS replace chlorine?
No. It oxidizes waste but does not sanitize. Keep free chlorine at 3 to 5 ppm or bromine at 4 to 6 ppm.