Marine Depot offers FREE economy shipping for most products when you spend $29 or more! Your order will be delivered in up to 7 business days after it ships out. Economy shipping methods include UPS Ground, USPS First Class, and/or SurePost. You can also upgrade your shipping to Faster Shipping which speeds delivery to 1-5 days. A shipping upgrade is $2.99 for orders under 20 lbs, $3.99 for orders 21-40 lbs, and $4.99 for orders over 41 lbs. Orders placed before 10:30 am PST Monday-Friday are shipped the same day. Free shipping is only available within the contiguous United States. Frozen foods, live foods, and items shipped directly from the manufacturer do not qualify for this special offer.
Free Upgraded Shipping For Orders $250+
Most orders over $250 qualify for FREE upgraded shipping! Your order will be delivered 1-5 days after it ships out. Thanks to Marine Depot's two strategically located warehouses in Nevada and Georgia, over 90% of shoppers receive their orders within 1-2 business using this level of service. Orders placed before 10:30 am PST Monday-Friday are shipped the same day. Free shipping is only available within the contiguous United States. Frozen foods, live foods, and items shipped directly from the manufacturer do not qualify for this special offer.
$2.99 Flat Rate Shipping For Orders Under $29
Most orders under $29 ship for only $2.99 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. Orders placed before 10:30 am PST Monday-Friday are shipped the same day. Our $2.99 flat rate shipping is only available within the contiguous United States. Frozen foods, live foods, and items shipped directly from the manufacturer do not qualify for $2.99 flat rate shipping.
Frozen foods are delivered 1-3 business days from the day your order ships. Frozen foods are shipped every Monday and Tuesday. Shipping cut-off is Tuesday at 10 am PST (1 pm EST). Orders received after 10 am PST on Tuesday will be shipped the following week. Shipping and handling is a $19.99 flat-rate charge so you can order as much or as little as you like.
Orders not shipped within the contiguous United States—the 48 U.S. states on the North American continent south of Canada plus the District of Columbia—are considered international orders. International orders are not eligible for Marine Depot’s free shipping promotions and additional surcharges may apply. It is important to note that not all products we carry can be shipped internationally. Any brokerage fees, tariffs and/or taxes will be billed to you directly by the shipping courier. International customers must use the same billing and shipping address.
Tests tap water and freshwater aquariums for general hardness (GH) and carbonate hardness (KH). Helps detect stress on fish caused by rapid pH shifts, which result from low KH levels and helps aquarists duplicate the natural habitat of their fish.
KH & GH Test Instructions:
What is Carbonate Hardness (KH)? Carbonate hardness (also known as alkalinity) is the measure of carbonate (CO32-) and bicarbonate (HCO3-) ion concentrations dissolved in water. These minerals are present in municipal, well, and bottled spring water. The level of carbonate hardness in tap and bottled water depends on the source of the water and the treatment processes it has undergone. Carbonate hardness helps stabilize pH in the aquarium. An aquarium with a low KH level (50 ppm or less) will tend to be acidic. Aquariums with very low KH are subject to rapid pH shifts, if not monitored carefully. Water with a high KH level (= 200 ppm) usually has a high pH. The Aquarium Pharmaceuticals KH (Carbonate Hardness) Test measures KH in German degrees (°dKH). To convert °dKH to parts per million (ppm), multiply °dKH x 17.9.
Directions for Testing Carbonate Hardness (KH):
Read thoroughly before testing. Do not allow Test Solutions to get into aquarium.
To remove childproof safety cap: With one hand, push red tab left with thumb while unscrewing cap with free hand.
Rinse a clean test tube with water to be tested.
Fill the test tube with 5 ml of aquarium water (to the line on the test tube).
Add Carbonate Hardness Test Solution, one drop at a time, holding dropper bottle upside down in a completely vertical position to assure uniformity of drops. After first drop is added, solution will turn blue. If the water sample contains only 1°dKH, the solution will turn from clear to its yellow endpoint after the first drop is added.
Cap the test tube and invert several times after each drop. Keep count of the drops being added. Do not hold finger over open end of the tube, as this may affect the test results.
The test is completed when the water in the test tube, after having been shaken, turns from blue to yellow. If you have difficulty discerning the color after the first drop of test solution is added, remove the cap from the test tube and while holding it over a white background, look down through the tube.
The Carbonate Hardness value is determined by the number of drops of the reagent that must be added to turn the water in the test tube bright yellow. Each drop is equal to 1 °dKH or 17.9 ppm KH, (see the chart).
What is General Hardness (GH)? General hardness is the measure of calcium (Ca2+) and magnesium (Mg2+) ion concentrations dissolved in water. These minerals are present in municipal, well, and bottled spring water. The level of general hardness in tap and bottled water depends on the source of the water and the treatment processes it has undergone. Hard water (= 200 ppm) is high in calcium and magnesium, while soft water (50 to 100 ppm) is low in these minerals. The Aquarium Pharmaceuticals GH (General Hardness) Test measures GH in German degrees (°dGH). To convert °dGH to parts per million (ppm), multiply °dGH x 17.9.
Directions for Testing General Hardness (GH):
Read thoroughly before testing. Do not allow Test Solutions to get into aquarium.
To remove childproof safety cap: With one hand, push red tab left with thumb while unscrewing cap with free hand.
Rinse a clean test tube with water to be tested.
Fill the test tube with 5 ml of aquarium water (to the line on the test tube).
Add General Hardness Test Solution, one drop at a time, holding dropper bottle upside down in a completely vertical position to assure uniformity of drops. After first drop is added, solution will turn orange. If the water sample contains only 1°dGH, the solution will turn from clear to its green endpoint after the first drop is added.
Cap the test tube and invert several times after each drop. Keep count of the drops being added. Do not hold finger over open end ofthe tube, as this may affect the test results.
The test is completed when the water in the test tube, after having been shaken, turns from orange to green. If you have difficulty discerning the color after the first drop of test solution is added, remove the cap from the test tube and while holding it over a white background, look down through the tube.
The General Hardness value is determined by the number of drops of the reagent that must be added to turn the water in the test tube green. Each drop is equal to 1 °dGH or 17.9 ppm GH (see the chart).
GH and KH in the Aquarium Aquarists seek to provide a healthy aquarium environment by duplicating the water conditions of the natural habitats of their fish. Tap water rarely provides the water conditions necessary to maintain an optimal aquarium. Some tap water supplies have a very low KH level (below 3 °dKH). This type of water has very little pH buffering capacity and can contribute to wide pH swings in the aquarium. When water evaporates from the aquarium, it leaves behind hardness ions. Topping off with tap water simply adds more minerals to the aquarium, resulting in a steady increase in GH. It is therefore necessary to test the GH and KH frequently to monitor water quality and prevent stressful conditions from occurring. Use the table below to create the ideal water hardness levels for your aquarium fish. When keeping a community aquarium with a variety of tropical fish, adjust the GH and KH to 3° - 6° (50 - 100 ppm).
GH & KH RANGE - Aquarium Life 0°-3° (0-50 ppm) discus, arowanas, elephantnose, neons, cardinals, live plants
3°-6° (50-100 ppm) Most tropical fish including angelfish, cichlids, tetras, botia, live plants
6°-11° (100-200 ppm) Most tropical fish including swordtails, guppies, mollies, goldfish
11°-22° (200-400 ppm) Rift lake cichlids, goldfish, brackish water fish
Reducing General Hardness General Hardness can be lowered with Aquarium Pharmaceuticals Water Softener Pillow. The ion exchange resin in the Water Softener Pillow lowers GH by removing calcium and magnesium ions. The Water Softener Pillow will not lower KH. Partial water changes with deionized water will gradually reduce GH to the desired level.
Increasing General Hardness African cichlids and brackish water fish require hard water with a pH of 8.2. Commercially available African cichlid or marine salts will increase GH and KH levels.
Lowering Carbonate Hardness ALowering KH is best accomplished by diluting the aquarium water with deionized water. Deionized water contains no KH or GH. Partial water changes will gradually reduce KH to the desirable level.
Increasing Carbonate Hardness KH can be increased with Aquarium Pharmaceuticals PROPER pH™ buffers. PROPER pH 6.5, 7.0 and 7.5 are non-carbonate buffers that automatically adjust pH and increase KH. PROPER pH will raise or lower pH, stabilizing it at the pre-set pH level. PROPER pH 8.2 is a carbonate buffer suitable for marine and African cichlid aquariums.
Harmful:
KH TEST Causes burns. In case of contact with eyes or skin, flush with water for 15 minutes and seek medical attention immediately.
GH TEST contains Triethanolamine.
Harmful by inhalation.
Irritating to eyes, respiratory system and skin. If in contact, flush with water for 15 minutes and seek medical attention immediately.
Keep out of the reach of children.
Manufacturer Info
Aquarium Pharmaceuticals Aquarium Supplies Aquarium Pharmaceuticals (API) has been helping people take good care of ornamental fish for over 40 years. Their research and development scientists have advanced the care of fish with all-natural medications, stable bacteria for biological filtration, one-bottle test kits, consumer-friendly dosing caps and much more. They’ve received over 25 global patents for their breakthrough innovations in the aquatics industry. And they continue to look for ways to improve the fishkeeping experience for hobbyists. Research. Experience. Dedication to scientific, quality treatment for healthy fish. It’s what makes API the first choice of aquarium owners. API manufactures and sells hundreds of products across many different product categories, including aquarium and pond treatments, aquarium equipment, aquariums and fish nutrition.
Ask a Question Earn 15 Points when you answer a question
This product isn't as in depth as some of the other kits on the market, but is very accurate with what it has, and it measures the water hardness well enough for the average aquarist. I have used it for many years, I like it's performance and it's low cost.
The API GH & KH tests are easy to use and interpret. Dip sticks can leave you guessing wher you fall between a 20 degree and 40 degree reading but with this adding the drops and counting makes it easy to get an accurate number. Won't use any other type of test.
I have used the API series of test kits for several years. I use the Freshwater Test Kit for most tests and complete the testing with the GH/KH test kit. This review will cover just the GH/KH kit. KH is another name for Alkalinity and is a very important test for fish keepers who have little alkalin...Read More
I have used the API series of test kits for several years. I use the Freshwater Test Kit for most tests and complete the testing with the GH/KH test kit. This review will cover just the GH/KH kit. KH is another name for Alkalinity and is a very important test for fish keepers who have little alkalinity in their water. If your water runs out of alkalinity (low KH) you will have a pH crash. This is severe and may cause all your fish to die. This can be prevented by monitoring your KH on a regular basis. As long as it is more than 70 (or 4 drops on the KH test) your water is OK. If less - add Baking Soda. The test is easy and quick. With water in the test tube, add the reagent one drop at a time (cover and shake after each drop) until the test water changes from blue to yellow. That number of drops is your KH or can be converted to ppm alkalinity.
The GH test kit tells you how much minerals like Ca and Mg are in your water. The test is done the same way.
These test kits are ideal for pond keepers to keep an eye on their water. They are inexpensive and easy to use. The results are reliable. When teaching Water Quality classes, I recommend these API test kits to my students.Hide
Most orders under $29 ship for only $2.99 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.
free shipping for orders $29+
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 $29 or more!
free faster shipping for orders $250+
Over 90% of shoppers receive their orders within 1-2 business days. Upgrade from free economy shipping to faster shipping for only $2.99—or spend $250 and we'll upgrade you automatically!
need your order even faster? no problem!
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.
buy it today and we'll ship it today
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.
live plants, live foods, and frozen foods delivered to your door
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!
Earn 5 reward points for every $1 you spend to get 5% cash back Most Products
Earn 1 reward point for every $1 you spend to get 1% cash back Abyzz, American Marine, AquaIllumination, AutoAqua, CoralVue, Digital Aquatics, EcoTech Marine, Giesemann, GHL, Hanna Instruments, Hydor, IceCap, Innovative Marine, Iwaki, Kamoer, Kessil, Klir, Korallen-Zucht, Maxspect, Mur-lok, Nano Box, Neptune Systems, NYOS, Oceanbox Designs, Pax Bellum, Radium, Red Sea, Reef Glass, Reef Octopus, Seneye, Somatic, Tunze, Vertex Aquaristik, and Waterbox Aquariums
You can also get bonus reward points by purchasing select items during special sales and promotions.
46,020 Reviews. 5,153,553 Products Shipped. #1 Aquarium Supply Store Online.
If you find a product we sell for a lower price at another online store, we will match their price to ensure you always pay the lowest amount when you shop with us.
Enter the price, shipping cost and website address where you found the lower price. Then click the "Add to Cart" button. We will review the lower price while processing your order and make any necessary reductions before your order ships. Some restrictions apply. See Terms & Conditions
