Tetra Algetten, 12 tablets is a product for long-term algae control in aquariums and for prevention. According to the description, the concentration of active substances rises slowly, giving a gentle, long-lasting effect; within 4–7 days algae noticeably decrease and new growth slows. Dosage is 1 tablet per 10 L of water. The manufacturer asks you to read the label and instructions before use.
What the manufacturer claims
Tetra positions Algetten as a gentle product: the tablet dissolves gradually, releasing the substance evenly rather than all at once. This is less stressful for fish than sudden doses of liquid algicides. It is suitable both for fighting existing algae and for prevention.
Key specifications
| Parameter | Value |
|---|---|
| Type | algae control |
| Form | tablets |
| Dosage | 1 tablet per 10 L |
| Effect | in 4–7 days |
| Action | slow, long-lasting |
| Active ingredient | not stated in the listing |
| Quantity | 12 tablets |
| Barcode | 4004218140349 |
Pros
- Gentle action. The substance enters the water gradually.
- Prevention and treatment. Both in one product.
- Simple dosing. 1 tablet per 10 L.
- Visible results within a week. 4–7 days, per the description.
- Convenient form. No liquid to measure.
- Well-known brand. Tetra is one of the largest aquarium care makers.
Cons and what to watch
- Active ingredient not stated. The formula is not disclosed in the listing.
- No repeat dose interval. How often to add tablets is not stated.
- No compatibility data. Nothing about shrimp, snails or live plants.
- Odd translation. A confusing phrase about an "automatic dispenser".
How much water a pack treats
At 1 tablet per 10 L, a pack covers a single treatment of a 120 L aquarium. For a 60 L tank that is two doses, for 30 L four. Count the actual water volume, not the nominal tank size: substrate and decor take up 10–20% of the space.
Why algae appear
Algae thrive when there is plenty of light and few plants, when the water has excess nitrates and phosphates from overfeeding and infrequent water changes, or when the tank sits in sunlight. An algae product removes the symptom, but without fixing the cause the algae will return. Check your water parameters, for example with Tetra 6in1 test strips.
What to do alongside
Cut the lighting period to 8–10 hours, move the tank out of direct sun, feed fish moderately and change part of the water regularly. Remove algae from the glass and decor by hand before treatment. Fast-growing live plants compete with algae for nutrients — the best long-term prevention.
Safety for tank inhabitants
The listing does not say whether Algetten is compatible with shrimp, snails and sensitive plants. Read the label before use. Watch your fish during treatment: if they stay near the surface or breathe heavily, increase aeration and change part of the water. Dead algae decompose and can worsen water quality, so a water change after treatment is useful.
Filter and carbon
Activated carbon in the filter can absorb treatment substances. It is usually removed from the filter during treatment and put back afterwards to clear residues from the water. Check the label for this.
Alternatives
Tetra has a similar tablet product, AlgoStop Depot. To stabilise water parameters, try Tetra Easy Balance, and for live plants the PlantaMin fertiliser.
Who it suits
The tablets suit freshwater aquarium owners fighting algae films and filamentous algae or wanting to prevent them. In tanks with shrimp and rare plants, check compatibility on the label first. More products are in fish medicines and water care.
Verdict
Tetra Algetten is a gentle, long-acting anti-algae tablet, 1 tablet per 10 L, with results in 4–7 days. The downsides are that the listing does not state the active ingredient, the repeat dose interval or compatibility with shrimp and plants; without fixing the cause the algae will return.
FAQ
How many tablets should I add?
1 tablet per 10 L of water.
When will there be an effect?
In 4–7 days, per the description.
What tank size does a pack cover?
A single treatment of 120 L.
Is it safe with shrimp?
The listing does not say — check the label.
Should I remove carbon from the filter?
Usually yes, during treatment; check the label.
Can it be used for prevention?
Yes, the manufacturer allows this.
Will the algae come back?
Yes, if excess light and nutrients are not addressed.
