Tetra AlgoStop depot, 12 tablets is a long-acting algae treatment for freshwater aquariums. According to the description, it fights all types of algae — green, brown and red — and prevents them from coming back. The highly concentrated product is released slowly and evenly, fully within 4 weeks, after which the tablets should be replaced to keep the effect going. The tablets do not dissolve and keep their shape. The dose is 1 tablet per 20 l of water. The manufacturer specifically urges safe use of algae products and says to read the label and instructions before use.
Key specifications
| Parameter | Value |
|---|---|
| Type | algae control tablets |
| Algae | green, brown, red |
| Action | slow release over 4 weeks |
| Replacement | every 4 weeks |
| Dose | 1 tablet per 20 l |
| Aquariums | freshwater |
| Quantity | 12 tablets |
Pros
- Long-acting. One application lasts 4 weeks.
- Even release. No sudden concentration spike.
- Works on several algae types. Green, brown and red.
- Prevention. Helps stop algae returning.
- Simple dosing. 1 tablet per 20 l.
- Tablets keep their shape. No crumbs clouding the water.
Cons and what to watch
- Active ingredient not stated. The card gives no composition.
- No compatibility data. Effects on shrimp, snails and sensitive plants are not mentioned.
- Does not remove the cause. Excess light and nutrients remain.
- Dying algae foul the water. A mass die-off lowers oxygen levels.
- No word on removing old tablets. They do not dissolve, but the description does not say to take them out.
How to use
Work out the number of tablets: 1 per 20 l of water. A 60 l tank needs 3 tablets, a 100 l tank 5. Place them on the substrate or in the flow, as the pack instructions say. After 4 weeks the product has been fully released, and the tablets are replaced to continue the effect. Always read the label before use, as the manufacturer advises, especially if you keep shrimp, snails or delicate plants.
Where algae come from
Algae appear when there is more light and nutrients than plants can use. Common causes are too long a photoperiod, direct sun, overfeeding, infrequent water changes and few live plants. Unless these conditions change, algae will return once the tablets stop working. Feeding without overfeeding is covered in aquarium fish food: how to feed.
Plants versus algae
The most reliable long-term defence is healthy, fast-growing plants that take up nutrients. Feed them with a liquid fertiliser such as Tetra PlantaMin, and give rooted plants Tetra Crypto tablets. Lighting should be adequate but not excessive; for nano tanks, for example, the AquaLighter Nano on an 8–10 hour schedule.
Oxygen during treatment
When algae die off in large amounts, their decay uses up oxygen and worsens the water. During treatment, increase aeration, for example with a Resun AIR-8000 air pump in large tanks, siphon out dead algae and change water.
Water testing
Test the water before and during treatment, especially nitrate and phosphate if your test covers them. Tetra Test 6in1 strips are a handy option. Products such as Tetra Easy Balance help stabilise parameters.
Manual cleaning
Before adding the tablets, scrape the glass, remove algae from decor and do a water change. That way the product has less algae to deal with and the water suffers less from their decay.
Storage
Keep the pack closed in a cool, dry place out of reach of children and animals.
Who it suits
Tetra AlgoStop depot suits owners of freshwater aquariums who have already adjusted light and feeding but want to beat algae faster and keep them from returning. Other products are in the fish medicines and water care section.
Verdict
Tetra AlgoStop depot is a long-acting tablet against green, brown and red algae, releasing evenly over 4 weeks at 1 tablet per 20 l. The downsides are that the active ingredient and compatibility with shrimp, snails and plants are not stated, it does not remove the cause of algae, and dying algae call for extra aeration and water changes.
FAQ
What is the dose?
1 tablet per 20 l of water.
How long does it last?
4 weeks, then the tablets are replaced.
Which algae does it target?
Green, brown and red.
Do the tablets dissolve?
No, they keep their shape.
Is it safe for shrimp?
The card does not say; read the label before use.
Can it be used in a marine tank?
No, freshwater only.
How much water does a pack treat?
12 tablets cover 240 l for 4 weeks.
