In Stock
Magnesium is a chemical element with the element symbol Mg. Magnesium is extremely important for most reef-inhabiting species, foremost however for corals. Magnesium in conjunction with calcium is responsible for the alkalinity (KH), i.e. the hardness of water. In a salt water aquarium, magnesium is consumed in significantly lower amounts than for example calcium. Nevertheless it should be monitored regularly.
The magnesium content in the water is dependent on the salt concentration. The natural concentration of magnesium in salt water is 1,310 mg/l (which equals a salt content of 3.5%). The lower the salt concentration, the lower the magnesium content. In practice, a reef aquarium should have a 1:3 ratio of calcium to magnesium. In other words, a calcium value of 400 mg/l should equal a magnesium concentration of approx. 1200 mg/l.
The Giesemann magnesium test offers an uncomplicated, fast and precise measurement of the magnesium concentration in salt water aquariums.
By the way: many artificial reef ceramics also release magnesium into the water. Therefore, especially for newly equipped aquariums, it is essential to monitor the magnesium concentrations closely.
With over 25 years’ experience, Giesemann Aquaristic has made a name as the world leader in aquarium lighting technology, illumination products and aquarium control systems. In their array of products, you will find all your aquarium needs including innovative modular furniture systems, technical installations for water treatment, test kits and other accessories.
Most orders under $39 ship for only $5.99 using a mix of economy shipping methods including UPS Ground, USPS First Class, and/or SurePost. Your order will be delivered in up to 7 business days after it ships out.
We ship 99% of the products we carry for free within the contiguous United States using a mix of economy methods including USPS First Class Mail, SurePost and UPS Ground. Your order will arrive in up to 7 business days. Just spend $39 or more!
Over 90% of shoppers receive their orders within 1-2 business days. Upgrade from free economy shipping to faster shipping for only $5.99—or spend $250 and we'll upgrade you automatically!
Expedited shipping services are available for most products if you are in a hurry. Get guaranteed delivery in 2 business days, 1 business day, or next day by 10:30 am. Costs vary by location.
Same-day shipping is available Monday-Friday for most products—place your order by 10:30 am PST. Pre-ordered and back-ordered items do not qualify, nor do drop-shipped, live, or frozen shipments.
We ship live plants, live foods, and frozen foods within the contiguous United States. Each of these categories is subject to its own $19.99 flat-rate shipping fee to cover the special packaging and/or expedited shipping costs required to ensure safe delivery. Orders with 12+ live plants ship free!
Return any new and unused item within 60 days for a full refund. Having difficulty with a product? Contact us to speak with an aquarium expert. If you need a replacement, fill out this form.
A small segment of the 180+ brands we carry require that customers contact them directly if/when problems arise. You can view the full list of those brands and get their contact info here.
We are unable to accept returns of Digital Aquatics, Neptune Systems, Vertex Aquaristik, Aqua Illumination (AI), EcoTech Marine, GHL, or Seneye products once the manufacturer's packaging seals have been broken.
Marine Depot is an authorized reseller for every product we carry. That means when you buy aquarium supplies from us, your products are not only backed by our own 60-day return policy, they also carry full factory warranties, where applicable. Some items have a 1-year warranty, others have limited lifetime warranties. Warranty coverage varies from manufacturer to manufacturer, so please read the product description of the item(s) you are considering thoroughly for details or contact us if you have warranty questions.
Rack up reward points to earn discounts on future purchases! You can earn reward points by creating an account, writing reviews, referring friends, subscribing to our newsletter, buying products, and more!
You can also get bonus reward points by purchasing select items during special sales and promotions.