Marine Depot offers FREE economy shipping for most products when you spend $29 or more! Your order will be delivered 1-7 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 UPS Ground which speeds delivery to 1-5 business 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 business 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 2 business using this level of service (UPS Ground). 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 1-7 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.
These are the highest quality industrial-grade Brass Check Valve from German Air Pressure Systems. They are heavy-duty enough for food-grade liquid as well. Just like you, we also thought that these were unnecessarily overkill for aquaristic purposes, but it has been proven that these are the ONLY qualified Check Valves for protecting your expensive CO2 equipment (Regulator & Cylinders) from saltwater with a pressurized Kalkreaktor pushing it backward vigorously. Takes 4/6 mm (ID/OD) or 1/8" airline tubing.
Manufacturer Info
Korallin Korallin is a German based company who is a manufacturer of specialized aquatic components and accessories for the advanced marine aquarist.
Ask a Question Earn 15 Points when you answer a question
I don't have salt water aquarium, but I have freshwater plant aquarium. At first, I thought it should be the best check valve in the market. Finally, I find out that, no, it's the best check valve. Why? When I figured out that my CO2 system had problem, I thought that should be my CO2 regulator ...Read More
I don't have salt water aquarium, but I have freshwater plant aquarium. At first, I thought it should be the best check valve in the market. Finally, I find out that, no, it's the best check valve. Why? When I figured out that my CO2 system had problem, I thought that should be my CO2 regulator or bubble counter's problem. Why? I thought it's the best check valve in the market. I ordered new CO2 regulator and bubble counter, and finally I found out, it's check valve's problem. It's expensive and it won't last long. Don't waste your money. Finally, I learned the lesson. I did not pay attention to another review, so I needed to suffer it.Hide
Purchased this in a kit with a calcium reactor, and had a very hard time setting up and adjusting the bubble count and maintaing pressure. Turns out the product was defective from the beginning. It would not hold pressure or maintain a consistent bubble count. It would never restart after my cont...Read More
Purchased this in a kit with a calcium reactor, and had a very hard time setting up and adjusting the bubble count and maintaing pressure. Turns out the product was defective from the beginning. It would not hold pressure or maintain a consistent bubble count. It would never restart after my controller cut off the regulator regardless of the pressure it was set on. I do appreicate Marine Depot's customer service as they took care of the issue with not fuss once the problem was isolated. Save yourself the TIME and money and I would recommend going with the cheaper plastic one, as I was up and running in no time once I installed the replacement.Hide
First thing I noticed was that the pressure required to "open" valve was around 5PSI. This was with a Geo 624 calcium reactor with Maxijet 1200 feed pump, Harris 2 stage regulator. When the bottle emptied in ~ 3 months the check vavle fialed and allowed water into my equipment. What more c...Read More
First thing I noticed was that the pressure required to "open" valve was around 5PSI. This was with a Geo 624 calcium reactor with Maxijet 1200 feed pump, Harris 2 stage regulator. When the bottle emptied in ~ 3 months the check vavle fialed and allowed water into my equipment. What more can I say, it didn't work.Hide
This was my 3rd replacement for the brass check valve that came with the Koralin calcium reactor all wich failed. I switched to the Dennerle check valve and have been very happy with the results. When ever my tanks have emptied water found its way into the valve. Sorry for the poor review but it jus...Read More
This was my 3rd replacement for the brass check valve that came with the Koralin calcium reactor all wich failed. I switched to the Dennerle check valve and have been very happy with the results. When ever my tanks have emptied water found its way into the valve. Sorry for the poor review but it just does not hold up!.Hide
I have owned a calcium reactor for several years now. I have had 2 or 3 of these brass check valves fail over time. It will work for a while then it starts locking up and not allowing CO2 flow. This makes dialing in the bubble/minute count a huge issue. I know it is the check valve and not the r...Read More
I have owned a calcium reactor for several years now. I have had 2 or 3 of these brass check valves fail over time. It will work for a while then it starts locking up and not allowing CO2 flow. This makes dialing in the bubble/minute count a huge issue. I know it is the check valve and not the regulator as when I took it off I have been fine. Try an alternate.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 1-7 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 1-7 business days. Just spend $29 or more!
free faster shipping for orders $250+
Over 90% of shoppers receive their orders within 2 business using UPS Ground. Upgrade from free economy shipping to UPS Ground 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
