Jul
Water Parameters
What Level of GH is Good in Planted Aquarium
An Introduction to GH in Aquariums
As an aquarium beginner, you will need to know what GH level is appropriate for your planted aquarium.
Today, we’ll answer the question of what level of GH is good in a planted tank environment. GH in the tank above was about 10-12, with KH values of around 8-11 due to the limestone used in the tank. I would classify such water parameters as moderately hard; even then 95%+ of available commercially traded aquatic plants would grow well in such conditions.
What is GH (General Hardness) in an Aquarium?
Despite its fancy name, GH (or general hardness in your tank) is simply the measurement of the total amount of Ca/Mg ions in the water (and other divalent cations). Calcium is present in most tap water. However, magnesium is often over-looked.
If your tank has high GH, it can be that all of it is made out of Calcium ions, and no magnesium is present – in this case, magnesium still has to be dosed. Such data can often be found in local water reports.
Facts About GH in Aquariums
- • Generally, hard tap water comes from limestone(CaCO3) regions. It’s much more common to see high GH values with corresponding high KH values. However, these values do not have to match. It is possible to have high GH, low KH water. [Lots of Ca/Mg but no Carbonates] It is also possible to have low GH, high KH water. [Low amounts of Ca/Mg in water, but plenty of carbonates].
- • Plants and livestock are generally less sensitive to GH than KH. Plants that require soft water to grow well require low KH values, but not necessarily low GH values. These plants are sensitive to alkalinity, to be accurate, rather than General hardness. GH is important when keeping shrimp and shellfish.
- • Soft water planted tanks typically have GH as low as 1-3. While very hard water tanks can have GH values in the 20+ dGH range. Shrimps and snails appreciate having calcium in the water, having 3 – 5 GH is beneficial.As calcium is present in most tap water, calcium deficiencies are very rare in planted aquariums. Almost all cases of tip stunting attributed to calcium deficiency are mis-diagnosed and are caused by other variables instead.
- • Having 15ppm of Calcium and 5ppm of Magnesium will work fine for most tanks. Some plants such as Downoi and Rotala sunset favour higher GH levels.
GH Measurements in dGH and ppm
Very Soft
- • GH (in dGH) 0-4 dGH
- • GH (in ppm) 0-70 ppm
Soft
- • GH (in dGH) 4-8 dGH
- • GH (in ppm) 70-140 ppm
Medium
- • GH (in dGH) 8-12 dGH
- • GH (in ppm) 140-210 ppm
Hard
- • GH (in dGH) 12-18 dGH
- • GH (in ppm) 210-320 ppm
Very Hard
- • GH (in dGH) 18-30 dGH
- • GH (in ppm) 320-530 ppm
Aquarium GH FAQs
As mentioned earlier in the article, GH refers to the general hardness of the aquarium water, or the dissolved concentration of magnesium and calcium ions. When we talk about the preference your fish have for a certain level of “soft” or “hard” water, this is GH (which is different than KH, or carbonate hardness).
If the GH in your aquarium is too high, you will likely have stressed out or ill fish. To lower the GH safely in your aquarium, you will need to perform frequent water changes, which dilutes the amount of fish waste in the tank. You can also change out the type of water you are using in your aquarium. For example, you can use reverse osmosis (RO) or distilled water. Another way to lower GH in aquarium(s) is to utilize water softening crystals, which are salt mixes specifically designed for aquarium use.
Are you seeing lethargic, dull-colored fish in your tank? You will need to raise the GH in your aquarium. We recommend using crushed coral either in your substrate, or in a filter media bag in your filter. Alternatives include Seachem Equilibrium or wonder shells. Be sure to test your water chemistry parameters often to prevent your GH from decreasing too much and causing ill fish and inverts. Check out SevenPorts’ testing and controllers products here to measure GH, KH, and pH in your tank.
You will want to maintain your levels between 6-12 dGH, depending on the species of fish you have in your planted aquarium. Some fish require much softer water, while others need harder water. For example, South American Cichlids prefer very soft/soft water, so you will want to keep your dGH lower at 3-5dGH. Livebearers and African Cichlids like their GH on the higher side.
When Should You Raise GH?
- Using RO/DI water (which has zero GH)
- Tap water is too soft (low mineral content)
- Livestock like shrimp/snails need more calcium/magnesium
- Plants show deficiency symptoms
When Should You Lower or Control GH?
- Your tap water is very hard (high GH)
- You’re keeping soft-water species (e.g., Caridina shrimp, Discus)
- You want to replicate biotopes like Amazonian rivers
Step 1: Test GH Before Adjusting
Product: General Hardness (GH) Fritz Test Kit
Link: https://sevenports.com/product/general-hardness-gh-fritz-test-kit-fresh-and-saltwater/
Ensure accuracy before making any adjustments. It’s the first step to success.
🔧 Products to Raise GH
1. Caridina GH+ 250ml
Link: https://sevenports.com/product/caridina-gh-250ml-shrimp-in-all-planted-aquaria/
- Each ml raises GH in 10L by 1 dGH
- Contains ideal ratios of Ca, Mg, and K
- Perfect for remineralizing RO/DI water
2. GH Plus for Shrimp Tanks – 250ml
- Add 5 ml per 26 gallons to raise GH by 1 dGH
- Simple and effective for shrimp aquariums
- Safe for Neocaridina and Caridina species
Link: https://sevenports.com/product/equilibrium-300g/
- Raises GH using calcium, magnesium, and potassium
- No sodium or chloride content
- Enhances mineral balance and plant vitality
Link: https://sevenports.com/product/equilibrium-600gm/
- Same GH-raising formula as 300g
- Economical size for larger systems
- Ideal for planted and high-turnover aquariums
⚠️ How to Lower or Control GH
Link: https://sevenports.com/product/acid-buffer-70g/
- Non-phosphate acid buffer for planted tanks
- Helps counteract high mineral content
- Use with RO/DI or soft source water
6. Dilution Method: Use RO/DI or Soft Water
- Use RO/DI water for water changes
- Remineralize with GH-raising products
- Avoid calcium-rich substrates or decor
- Use peat or buffering substrates for soft-water biotopesSource: https://sevenports.com/2022/12/01/reverse-osmosis-ro-filter-guide/
📃 Target GH Levels by Aquarium Type
📆 Best Practices for Adjusting GH
- Always test before and after changes
- Adjust GH gradually over several hours or days
- Match temperature and pH during water changes
- Avoid sudden swings in GH to prevent stress
📅 Final Thoughts
Maintaining proper GH ensures healthy livestock, thriving plants, and a stable aquatic ecosystem. SevenPorts offers a complete line of GH-adjusting solutions for every aquarium type—from shrimp-safe conditioners to bulk mineral supplements.
Contact Sevenports
Are you a beginner getting started with your planted aquarium? You’ll need to be equipped with knowledge of GH in your aquarium. Simply contact the experts at SevenPorts today for more information by giving us a call at 1 (626) 333-5372.
Read more about water parameters here, where we go into more depth about GH, TDS (total dissolved solids), pH (water acidity/alkalinity), and KH (carbonate hardness).