I've had a look at the mod now. It offers far more than I first tought and is definitely a plus for all players who like rich plantlife and farming-like activities. It also adds nice, expensive blocks.
Here's a more detailed look-on:
First: You ought to advertise it more by showing in the first posting of the thread what can be done with it - and how. Introduce the blocks and crafts shortly, show how to go from algae found to the end-product, show how the bleacher works and what it's good for. Show the shell-covered glass blocks - I'm sure a lot of people will like the mod for them alone! Right now, understanding the mod requires too much code reading.
Killing a living clam is close to impossible - even a strong sword does not seem to deal enough damage in the short time the clam can be wounded. It looks a bit odd if you drown while wielding the strongest sword and utterly fail to combat against a poor, defenseless clam :-) Maybe you could introduce nets to catch them. Sapiers mobf mod has some. Caught clams could remain alive until they're "crafted" to crushed shells. Maybe all the abms could run more often.
Producing the colored glass is quite expensive. It ought to remain whole when digged.
Dyes could be created from the algae themshelves by adding something. Perhaps you can take the old receipe for the dye base from unifieddyes that's not used anymore (glass bottles, bucket of water, junglegrass) and offer the old liquid dyes for a combination of such a dye base and algae. To get the "modern" pulver, it could be placed into the bleacher. That's a much more complicated process then than the current dye production - but why not? The liquid dyes could be required for the glass production instead of the algae themshelves.
Your lightglasses could also be supported by my colormachine if you want to. The white one could be turned with dye into colored ones and vice versa. That should have little effect on the production cost.
It would be nice if the bleacher got an inventory and would work similar to a furnace, only without fuel.
Regarding the code, please don't use copy and paste if the only part that varies between the copies is the name of the color. Use a function instead. Saves you changing everything three times :-)
Now, to the second part, the seaplants: I'm amazed that it works. Didn't know so many nodeboxes where possible. I ran into trouble with way less of them. But right now it all worked fine (slightly better hardware, and, most of all, recent MT version). The plants are amazingly detailed. They look very fine. Only...it's a bit vasted because you usually don't see many of them. Perhaps the detailed versions could be kept for rare occasions like aquariums? Something you bring home to your house after a long life as an explorer? A nodebox version with far less nodeboxes would be better for the everyday-seaplants. See the bamboo mod for example. Or papyrus in technic. They all look good with way less nodeboxes.
The approach you took here - with the plant beeing a nodebox extension of the node below - can be taken in a slightly diffrent way with drawtype plantlife as well. It is...hacky, but you wouldn't get killed from the coredevs (they promised :)): Instead of using the node below the plant (the one that forms the ocean floor), use one node below the ocean floor for a plantlike node. To get the plant large enough so that you can really see it above the ocean floor, give the node a sufficient high value for visual_scale (i.e. visual_scale = 2.5 ). The image of the plant will then streach out far enough. This is true for the bottom as well; perhaps the texture ought to be transparent there or posess some roots. It will also need a higher resolution than usual because it gets magnified so much (we need it to be large enough to show on top!). Second problem: If you just placed a normal node above the plant (as ocean floor), the plant would become black. The node it sits in needs to receive light. Even that can be solved: Create a special block that has "sunlight_propagates = true" set and is a normal node (with all the textures you want). Additional bonus: The images can even be animated. See the torch for that! So seaplants could move in the current of the water and thus look even better (provided a skilled artist does the textures - that's beyound what I can do).
Example of the dandelion yellow from homedecor, with 256px resolution, only changes are adaption of the selection box and "visual_scale = 2.5":
You can find a code sample
on pastebin. It's mostly default nodes changed slightly so that they work in the underwater setup. The torch is fun :-)