Diatoms?

[Juniormerve]

Tanks about 7 weeks old, came home from work a few days ago and noticed brown stains on rock, glass, and sand. Added some margarita and trochus snails, they've been going to work on it. What does this look like to you guys? I am hoping its just diatoms. Tank was cycled with dry rock, live sand. Current occupants include

 

GSP, Frogspawn, Hammer coral

 

1 small clown fish

 

1 blood shrimp, 3 trochus, 2 margaritas, 5 nassarius, 1 dwarf blue leg hermit...also a sand sifter starfish which is most likely going back to the LFS (bought on whim, then decided to read up on them...)

 

All added separately within the last 3 weeks.

 

The tank is a 20G high

Ammonia 0

Nitrite 0

Nitrate <40 (just added chaeto in fuge, about to do a 30%ish water change, or should I hold off?)

Ph - 8.0 (dropped from 8.2 within the last 2 weeks?)

Phosphate - <0.25

Calcium - 420

Magnesium - 1425

Alkalinity - 10.08 dKh

Salinity - 1.024 (with next water change, trying to bump it to 1.025)

Temp - 80.5°f

 

I have been using tap water with conditioner, recently bought a couple gallons of distilled to do a water change and see if that helps whatever bloom I am getting, or maybe hold off for now?

 

Colour wise, it looks like diatoms in every picture or video I have seen. Im confused as to the parts that contain bubbles, and there are a few areas that are a bit stringy, where as the other parts are basically encrusting.

Also the sand looks a bit aerated in some spots, like a sponge.

 

If this is just diatoms, I have read people suggesting to cut the light cycle. Wouldnt that be the opposite of what you want? If diatoms feed off the silicates in the sand, wouldnt it be better (or atleast quicker) for them to gorge out buffet style with the lights on and them starve themselves out?

 

 

 

 

 

 

 

[colinadam]

Looks like diatoms to me. 

I would add a nassarius snail for the sandbed to keep that stirred but otherwise this is a normal stage of reef keeping. 

 

Great looking rockwork, it looks awesome!

[Clown79]

Looks like diatoms.

 

Doing a waterchange is always beneficial, best method of nutrient removal/reduction. 

 

Using distilled is a good choice. Theres a good chance your nitrates are high from the tap.