Marineland 300 Gallon Deep Dimension Tank and Stand

marineland deep dimension 300As many of you know I recently bought the Marineland 300 gallon deep dimension aquarium setup. I had a few issues with it and have decided to make it my first product review. This review covers the tank itself as well as the stand, since you will usually buy and use the two together.


It is the largest manufactured (non-custom) aquarium on the market. It is 36″ front to back. This is 50% wider than any other tank. This makes it especially valuable for fish like stingrays, bichirs, arowanas, etc.


The overflow drains are only 1″. This greatly limits the amount of flow you can have running through the sump. In general 1″ drains can handle about 600gph, meaning this 300 gallon tank can only have about 1,200gph safely going through the sump. that’s only 4x turnover per hour (usual recommendation is 10x, and that’s for most freshwater tanks, not to mention ideal reef tank flow). This reduced flow makes getting adequate filtration more difficult.

The center braces are designed so that they dip in to the water. If you have really low flow they may clear it, but these dipping in to the water is a big, ugly distraction.

The openings in the end of the stand won’t fit a standard 75 gallon tank in as a sump. Even worst is that they don’t fit by only 1″. Just 1″ wider and they could handle a full 75. The company states that they are designed to handle the largest acrylic sumps on the market (which is true as far as I can tell, but I would also be surprised if there weren’t any acrylic sumps wider than 17″). This is absurd for such a large tank. It is very common for people to make their own sumps using standard tanks, this should be allowed for on a tank like this. They say the strength of the stand is a vital issue, and I agree. But, using thicker wood or doubling up the wood would allow it to have the needed strength while allowing for one single inch of extra width to the doors on the end. That is two easy options in three seconds that could avoid this problem without having any significant increase in manufacturing cost or even final retail price.

The stand is very short. The reason is because it needs to be able to fit through doorways sideways since it can’t upright. So the total height of the stand is only 27″ (same reason the tank is short). However, this makes it very difficult to work with any sump, especially one with a skimmer (and you need a REALLY good skimmer for a 300 gallon reef tank). This is such a problem that many people either build a second stand to lift the manufactured one and cut out the bottom so they can have the extra height, or have a stand custom built. Of course any alteration voids the warranty on the tank, which brings us to our last major problem:

They leak. Apparently the 300 gallon deep dimensions have a really bad tendency to leak. It is so bad that it is hard to talk to people with experience with them without this coming up. I talked to one aquarium service guy who said he has personally known 9 of them to leak. Then when it does leak the company hassles the owners of these tanks, especially if they have a custom stand (even if it is better and stronger than their manufactured tank). I had heard a little about this before I bought mine, but hadn’t heard it was such a bad trend. I read that they have made some improvements, but I am not sure if this is really the case or if those improvements will actually make the difference.


I intended to get a 300 deep dimension tank, but I wasn’t actually planning on doing it yet. I had planned on getting a 265, but when the sale was on the 3oo was actually cheaper, so I went for it. I don’t regret it. It is a nice, big tank. But if it leaks I will definitely regret it.

In general I would say stick with other tanks. Most of the times that a 300 would be a great option, a 265 will also be a great option but less likely to have these other problems. So unless you have one of the fish that really need a 36″ wide tank, go for a 265. And if you do have fish that really need the extra width, at least look in to a custom built glass tank (not from