I guess I should post this under the corydoras board but Aquaduk told me some surprising stuff. Algae Wafers aren't good for feeding to your corydoras. They will eat algae wafers, but they normally don't so they get digestive problems and causes pollution. Just telling...that's all.
I don't think this is actually a bad thing as was mentioned. Yes they will eat the algae wafers and yes it might cause them to produce more waste, but that isn't because of something bad... it's actually something good. Ever heard of the term "roughage" when talking about a healthy diet for humans? It has to do with getting enough fiber in your diet. Fiber is the part of food that can't be broken down by enzymes while being processed by your body. So it doesn't offer any nutritional value to your diet, however, it is key in preventing constipation and keeping intestinal disorders down to a minimum. And where does almost all fiber come from? Plants. In fish, most of the food that we feed them has a high fat content. This is a good thing because it helps make hardy fish with vibrant colors. However, just like in humans, too much fat in your diet can clog all kinds of things in your body. And that is where fiber comes into play. With a healthy diet of fiber enriched foods or (for fish that will eat them) plant based foods of which algae is one, you will help your fish... uh... well... they will poop regularly. Which is what you want as a constipated fish can very quickly become a dead fish. I feed my fish with food that has Spirulina in it like the one's from O.S.I. Though others like Hikari also contain spirulina if you look at their ingredients, I am slowly switching over to mostly O.S.I. products because it's the only one I've found that doesn't contain things like Ash and Phosphorus which are things you don't want in your tank.
though I've been using their for my Cory Cats because of it's little bit more protein and fiber(though they might be a bit small for your marble substrate). I haven't tried the wafers, but the only problem I've had with these pellets is that some of them don't want to sink and I just toss those. There are so many in the container and I only feed 2-3 pellets at a time for my 3 cats that I figure I would have to throw out half the container anyway when they went bad. So it doesn't bother me, but thought I would mention it so no one blames me ;D. However, I also feed my cats their and I haven't had a single one that wouldn't sink right away plus the cats LOVE them.
Since Corydoras are omnivores, there is no problem feeding them algae wafers as a supplement....Mine will eat them readily and haven't shown any sign of a problem. I wouldn't feed them as the sole source of food, but now and then a half or quarter of a wafer won't hurt.