Excess nutrient export with macroalgae

[Mcasteel]

I currently have a 75 gallong display tank and a 38 gallon sump/refugium below it. The majority of the refugium is full of chaetomorpha macroalgae. I prune it frequently and I assume it is absorbing excess nutrients.

I have a separate 15 gallon tank that I use for quarantine. If I prune half my chaeto, add it to the 15 gallon tank, which has no excess nutrients in it and expose it to sunlight for a certain length of time, will it eventually use up it's supply of nutrients? When I add it back to the refugium, would it absorb more nutrients and in a quicker amount of time?

I was thinking about this the other day because the chaeto sits in the refugium and absorbs nutrients and grows bigger. I assume the chaeto uses some nutrients to grow, but it is storing the rest. I guess you could equate this experiment to adding a slightly wrung out sponge to a glass of water and adding a totally wrung out sponge to a glass of water. If it worked, it might be a way of exporting nutrients out of the system quicker.

Any thoughts?

[snorvich]

You cannot recycle chaeto. Give it away, sell it, or throw it away. I suspect that it would make excellent fertilizer in the garden but have never tried that.

[LisaD]

I just prune mine, and it grows back. I don't see any reason to starve it, then put it back. I don't think excess nutrients are "stored", I think they are put into new growth. export the nutrients by getting rid of some of the chaeto, periodically. I think the growth rate is proportional to the nutrients it is using. when I prune, it grows back very quickly.

[airinhere]

I think there is a misunderstanding about how nutrient export via macroalgae works here.

The nutrients are not soaked up like a sponge.

The nutrients are utilized as food for growth of the macroalgae.

Just like feeding your fish or corals/ Some of the food/nutrients are utilized right away and some are not. Of the nutrients/food used right away, there is some form of waste release.

This is either in respiration of the macroalgae or releasing of other material into the tank.

As the macroalgae grows larger, it has used up larger and larger amounts of nutrients/food available in the tank system.

By physically removing the excess macroalgae, you are physically removing the end product of the nutrient uptake.

In effect, you are manually removing excess nutrients.

Starving your macroalgae will only result in unhealthy macroalgae. If anything, this will cause the remaining macroalgae to grow slower and be less effective as a form of nutrient export.

Provide sufficient lighting and regular manual removal of excess macroalgae is your best bet for efficient nutrient export from your macroalgae.

[LisaD]

airinhere said it really well, that is what I meant too.