Sport / Swimming
Electrolytes For Swimming
Swimmers sweat in the water too: well-trained squad swimmers measured in a 27°C pool lost around half a litre across a session, and warmer pools and open-water races cost far more. LYTES stocks Redmond Re-Lyte, $1.00–1.25 AUD a serve in the tub with sticks and capsules for the pool bag, and LMNT, 1000 mg sodium per stick at $64.95 AUD for 30. Free metro shipping applies over $149 AUD, and every order dispatches from Wollongong in 12–48 hours.
What goes wrong in the water
Sweat you never see
In the pool, sweat is rinsed away the moment it hits your skin, so most swimmers assume they are not losing any. Well-trained squad swimmers measured in a 27°C pool still lost around half a litre of sweat across a training session, carrying roughly 1,000 mg of sodium in every litre.
A warm pool changes the maths
Sweat rate climbs steeply with water temperature: in one study the same swimmers sweated about 0.5 litres an hour at 23°C and 1.25 litres an hour at 32°C. A warm program pool or a humid indoor aquatic centre can more than double what a session costs you.
No bottle at the wall in open water
In an ocean swim or open-water race there is no pool edge to stop at, and elite swimmers in 5 km and 10 km races have been measured sweating 1.1 to 2.0 litres an hour. You start the swim with whatever sodium you put back beforehand.
Two sessions a day, one shortfall
Squad swimmers often train before school or work and again in the afternoon, so sodium lost in the morning set carries straight into the next one. In a lab comparison, swimmers' sweat was saltier than runners', which makes topping up between sessions worth the effort.
Sweat and sodium across a squad session or open-water swimTypical ranges for a trained swimmer across 90 minutes in the water. Pick the conditions to see what a session like this costs you, and what it takes to replace it.
Sweat rate0.5 litres per hour
Sodium in sweat1,000 mg per litre
Fluid lost over 1.5 hours0.8 litres
1 × 750 ml bottle
Sweat rate in the water rises steeply with water temperature and effort — the same set in a 32°C pool can cost more than double what it costs at 27°C, and an open-water race costs more again. Sweat sodium varies widely between swimmers, so use these figures as a starting point, not a prescription.
Sodium lost in the session
750
milligrams
Roughly 0.8 serves of a 1000 mg sodium electrolyte serve, or about 500 mg per hour across the session.
Plain water replaces none of it.
Pool figures come from two swimming-specific studies. A 2009 International Journal of Sport Nutrition and Exercise Metabolism study of 17 nationally ranked swimmers in training — Maughan, Dargavel, Hares & Shirreffs — measured a mean sweat rate of 0.31±0.1 L/h (548±243 ml per session) in 27.4°C water, with mean sweat sodium of 43±14 mmol/L (roughly 990 mg/L). A 2011 Science & Sports study of nine competitive masters swimmers over a simulated 5 km pool race — Macaluso et al., "Effects of three different water temperatures on dehydration in competitive swimmers" — measured sweat rates of 0.48±0.28, 0.76±0.36 and 1.25±0.37 L/h in 23, 27 and 32°C water. The cool-pool preset sits between the training (0.31 L/h) and race-pace (0.76 L/h) figures at around 27°C; the warm-pool preset follows the 32°C result. Open-water sweat rates come from a 2025 E-balonmano.com study of 45 elite swimmers in international 5 km and 10 km races — Gonzalez-Custodio et al. — which reported 1.14 to 1.99 L/h depending on water conditions; the open-water preset sits in the middle of that range for a non-elite swimmer. No published study we could find measured sweat sodium in open-water racing, so the warm-pool and open-water sodium presets step up from the pool figure toward the 65.4±5.5 mmol/L (roughly 1,500 mg/L) measured in swimmers exercising in the heat in a 2010 International Journal of Sports Physiology and Performance study — Henkin et al.. Hourly sodium replacement guidance falls back on the American College of Sports Medicine's position stand on exercise and fluid replacement (300–600 mg sodium per hour for exercise lasting over an hour). Use this as a starting point, not a prescription — see a sports dietitian for individual advice.
Brand in focus
Redmond Re-Lyte
810mg sodium. Real salt from an ancient seabed. Zero sugar. The best-value tub in our range for mixing bottles at home across a squad week, with single sticks and capsules for the pool bag.
- 810-1000 mg sodium per serve, from Redmond Real Salt
- Zero sugar, naturally sweetened with stevia
- $1.00-$1.25 a serve in the tub - our best-value tub format
- Free metro shipping over $149
- Dispatched same day before 12pm AEST
Brand in focus
LMNT
Zero sugar. 1000 mg sodium. Built for people who sweat. The highest sodium dose we stock in one stick per bottle, for warm pools, double-session days and open-water race mornings.
- 1000 mg sodium per stick
- Zero sugar, fasting friendly
- Free metro shipping over $149
Also stocked for swimming
Salty Variety Pack - 8 Sachets
Sodii
$16.90
Sodii - Single Sachet
Sodii
$2.75
Salty Pineapple - 30 Sachets
Sodii
$68.90
Salty Citrus - 30 Sachets
Sodii
$68.90
Salty Passionfruit - 30 Sachets
Sodii
$68.90
Salty Raspberry - 30 Sachets
Sodii
$68.90
Unflavoured - 30 Sachets
Sodii
$64.90
Salty Pineapple - 30 Serve Tub
Sodii
$63.90
Unflavoured - 30 Serve Tub
Sodii
$59.90
Salty Passionfruit - 30 Serve Tub
Sodii
$63.90
Salty Citrus - 30 Serve Tub
Sodii
$63.90
Salty Grapefruit - 30 Sachets
Sodii
$68.90
Salty Raspberry - 30 Serve Tub
Sodii
$63.90
Salty Kiwi - 30 Sachets
Sodii
$68.90
Salty Grapefruit - 30 Serve Tub
Sodii
$63.90
Salty Mandarin - 30 Sachets
Sodii
$69.95
Salty Kiwi - 30 Serve Tub
Sodii
$64.95
Salty Mandarin - 30 Serve Tub
Sodii
$64.95
Salty Chocolate - 30 Sachets
Sodii
$69.90
Salty Chocolate - 30 Serve Tub
Sodii
$64.90
Shop by formatPoolside, the format matters as much as the formula. Pick what fits your swim bag and your training week.
Sticks
Tip one stick into your bottle in the change room and leave it at the end of your lane for the swim-down. A box of sealed single serves lives happily in a wet swim bag.
Best for squad sessions and meet daysTubs
Best value per serve and scoopable to the dose you want. Mix a week of bottles at home before the early sessions start — Re-Lyte's tub works out at $1.00–1.25 a serve.
Best for high-volume training blocks mixed at homeCapsules
Re-Lyte also comes in capsules. Swallow them with water on the pool deck before you get in or straight after, with no mixing and no flavour.
Best for swimmers who would rather not drink a flavoured bottleSingle serves
Single LMNT sticks, Re-Lyte sticks and Sodii sachets from $2.75. Drop a couple in your kit bag for a carnival, a meet or an ocean swim you have travelled to.
Best for trying a flavour before you commit to a boxVariety packs
A season of early sessions is a lot of the same bottle. LMNT, Re-Lyte and Sodii all make mixed-flavour packs, so you can find the one you will actually drink.
Best for finding your flavour before buying a tub or 30-stick boxDon't forget the other half of fuelling
Electrolytes replace what you sweat out. Carbs replace what you burn.
Past about 90 minutes of hard training, sodium alone will not stop you fading. Gels and chews top up the carbohydrate a long set or an open-water race burns through, so you can dose salt and fuel separately instead of relying on a single mix to do both jobs.
Shop energy gels & chews
Not sure yet?
Three quick questions,
one recommendation
Answer three questions about how you swim and train and we'll point you at a brand to start with. Prefer the full version? Take the complete quiz.
How salty do you sweat on dry land?
How many sessions do you swim a week?
How do you like to take it?
Based on your answers, start with
LMNT
the highest sodium dose we stock, 1000 mg per stick, built for salty sweaters swimming most days
Shop swimming electrolytesFree shipping over $149
Shop now
Swimming and electrolytes, answeredAnswers to what swimmers ask us most. These same answers power the FAQ schema on this page.
Yes. The water rinses sweat away so you don't notice it, but a study of nationally ranked swimmers training in a 27.4°C pool measured about 0.3 litres of sweat an hour, roughly half a litre across a session, at around 990 mg of sodium per litre. Warmer water pushes that up quickly: another study measured 1.25 litres an hour in a 32°C pool.
The general guidance for exercise lasting over an hour is 300–600 mg of sodium per hour. A 90-minute session in a cool pool sits toward the lower end of that, while warm pools, hard sets and open-water races push toward the top. One serve of Redmond Re-Lyte (810–1000 mg sodium) or LMNT (1000 mg sodium) covers the calculator's cool-pool estimate for a typical squad session — see the calculator above for warmer conditions.
There's no pool edge to stop at, and longer races only offer set feed stations, so the sodium you take in beforehand does most of the work. A study of elite 5 km and 10 km open-water swimmers measured sweat rates of 1.1 to 2.0 litres an hour depending on conditions, and wearing a wetsuit increased the body weight swimmers lost. A bottle with a serve of electrolytes in the hour before the start, and another straight after you finish, is a simple routine.
Both are zero sugar and both replace real sodium. Redmond Re-Lyte carries 810 mg sodium (flavoured) to 1000 mg (Unflavoured) and 400 mg potassium per 5g serve, made with real salt from an ancient seabed; its tub is the best value we stock at $1.00–1.25 a serve, and it also comes in sticks and capsules. LMNT carries 1000 mg sodium, 200 mg potassium and 60 mg magnesium per stick, the highest sodium dose we stock, which suits salty sweaters, warm pools and double-session days.
For early-morning sessions, mixing a serve into a bottle the night before and drinking it on the way to the pool is the simplest habit. Keep a bottle at the end of your lane for longer sets, and have another serve after the session if you're training again that afternoon, so the morning's sodium loss doesn't carry into the next one.
Orders placed before 12pm AEST on a business day are dispatched the same day from our Wollongong warehouse, and every order dispatches within 12 to 48 hours. Metro shipping is free on orders over $149.
Not sure which brand suits you?
Take our quiz and we will match you to a brand and format based on how you ride, or start with a taster pack and try a few before committing to a full size.