Swedish Tap Water is Actually Better Than You Think
Caridina have a reputation for being difficult. Most online guides say you MUST have an RO filter, otherwise there's no point in even trying. But that's not true. Many Swedish municipalities have tap water that is actually an excellent starting point – and with the right substrate and a bottle of water conditioner, you can create an aquarium where Crystal Red and Taiwan Bee not only survive but actually thrive and reproduce.
WHAT DOES YOUR TAP WATER SAY?
Before we do anything, we need to understand what we're working with. Tap water in Sweden varies a lot between municipalities – but generally, Sweden has relatively soft water compared to large parts of Europe. This is an advantage for us shrimp keepers.
The easiest way to find out your values is to Google "[your municipality] water values" – most municipalities publish their analyses openly on their website or through their water utility. Look for GH (general hardness), KH (carbonate hardness), and pH.
Here's what typical Swedish tap water looks like compared to what Caridina need:
Parameter Typical Sw. tap water Caridina's target Status
GH 3–5 °dH 3–6 °dH | Good ✓
KH 2–4 °dH 0–1 °dH | Too high ✗
pH 7.5–8.5 6–6.8 | Too high ✗
TDS 80–150 ppm 80–150 ppm | Often good ✓
GH and TDS are often already quite good. The problem is KH and pH – and that's where active substrate comes in. If your municipality has a KH above 5–6, the method is more difficult, but for most Swedish households with a KH of 2–4, it works perfectly.
If you need to raise GH, use GH+
"KH below 4 is low enough for an active substrate to handle it entirely on its own. That's the key to this whole method."
THE SOLUTION: ACTIVE SUBSTRATE
Active substrate – often called "soil" in the shrimp world – is not just a bottom to plant in. It's a living chemical system that actively binds carbonate (KH) from the water and buffers pH downwards. As KH drops towards zero, the water loses its ability to "buffer pH" and pH is stabilized by the soil's own properties around 6.0–6.5.
It's elegant. You don't need chemicals, no pH adjusters, no advanced equipment. The soil does the job for you – provided your KH isn't too high to begin with. With typical Swedish tap water at KH 2–4, this is entirely possible.
Which substrate should you choose?
There are several good options on the market. The most proven in shrimp contexts are:
• Ebi Gold – popular among shrimp keepers, keeps pH stable for a long time and releases minimal ammonia.
• Fluval Stratum Plants&Shrimps– Good for both plants and shrimp but may leak ammonia initially.
• Tropica Aquarium Soil - Very mild and easy to use.
Avoid regular potting soil, sand, or gravel if you want to keep Caridina. They don't buffer anything, and pH 8 will remain pH 8.
⚠ IMPORTANT: Active substrate can leak ammonia in the first few weeks. Always run the aquarium without shrimp for at least 4–6 weeks. Measure ammonia regularly and add shrimp only when the value is 0 ppm.
WATER CONDITIONER – A MUST
Tap water contains chloramine and sometimes heavy metals – substances that are invisible to the eye but deadly to shrimp. It's not enough to let the water stand and air out. Chloramine, which many Swedish municipalities use instead of just chlorine, does not disappear on its own.
Before adding new water during a water change, you should always treat it with a water conditioner that neutralizes chlorine, chloramine, and binds heavy metals. Some reliable options:
• Seachem Prime
• SL-Aqua Stabilizer
Dose according to the instructions on the bottle, always in the new water before pouring it into the aquarium.
STEP-BY-STEP – HOW TO SET UP THE AQUARIUM
1. Choose a suitable aquarium
30–60 liters is a good size for beginners. Smaller volumes lead to faster water impact during changes, which increases the risk of stress. Larger volumes are more stable but more expensive to maintain.
1. Add active substrate
At least 5–7 cm deep for the soil to buffer effectively. Do not rinse the soil – this washes away some of the active ingredients. However, rinse all other decorations and plants thoroughly.
1. Fill with treated tap water
Add water conditioner to the bucket of tap water before filling the aquarium. Fill slowly so as not to disturb the soil – use a plate or similar to break the fall.
1. Run cycle for 4–6 weeks
Start filter and plants. Measure pH, KH, and ammonia every two weeks. pH should drop towards 6.0–6.5 and KH towards 0–1. Ammonia should be 0 before adding shrimp.
1. Add the shrimp
Acclimate carefully with the drip method for at least 2 hours. Caridina are sensitive to rapid changes in water parameters. Stressed shrimp = dead shrimp.
1. Maintenance and water changes
Change 10% of the volume once a week. Always use treated water at room temperature. Pour in slowly. Measure water parameters once a month to keep track of the soil's status.
HOW LONG DOES THE SOIL LAST?
Active substrate is a consumable. With tap water at KH 2–4, the soil works a little harder than if you used RO water, but it's still perfectly manageable. Expect the soil to lose its buffering capacity after about 1.5–2 years. You'll notice it when the pH starts to creep up towards 7 and the KH no longer drops as it should.
When that happens, it's time to change the substrate. It's a bit fiddly, but nothing strange.
QUICK GUIDE – THE MOST IMPORTANT THINGS
✓ Google "[your municipality] water values" and check your KH
✓ KH below 4? Then the method works – active substrate handles the rest
✓ Active substrate (EBI, Fluval, Tropica) automatically lowers KH and pH
✓ Always treat the water with water conditioner (Seachem Prime or SL-Aqua Stabilizer)
✓ Run a 4–6 week cycle before adding shrimp
✓ Goal: pH 6.0–6.5 · KH 0–1 · GH 4–6 · TDS 100–140 ppm
✓ Change substrate every two years
