How much nitrate can a chaetomorpha eliminate?

[Scoot]

Added some chaeto to my 75g, in my homebuilt refugium sump with some LR. There's about a softball-sized clump of it. Its a nice deep green color, its lit well, and seems to be growing over the last few days.

My nitrates have come down from above 10, to now to between 5.0 and 10, where usually every 4-5 days my nitates go from 10 to 20.

Is chaeto really capable of eliminating that much nitrate?

Should I let it grow until it fills the fuge, then start clipping it back to export it?

[dskidmore]

It all depends on conditions, but anything that uses photosynthisis can remove alot of nitrate under ideal conditions. A freshwater high light planted tank typically removes 1-4ppm NO3 per day. I havn't seen the same statistics for saltwater refugiums, but it wouldn't surprise me.

Trimming: Get a feel for how fast it grows. You don't ever want it to feel crowded, trim it before that point. Until you trim, you've only trapped the nitrate, not removed it. Dying or eaten plant matter will turn back into nitrate again. On the other hand, if you prune too severely, you will reduce the rate of nitrate removal untill the cheato bounces back. Make pruning part of your weekly maintenance, and remove about a week's worth of growth each time.