Why my 3-month tank has sand going dirty

[Jay365]

Hi Guys,

I have my 20g salt water tank set up 3 month ago. I have 2 clowns, 2 snails and 1 turbo snail. I put dead rock and live sand when I set up my tank.
The problem is the sand is turning dirty (red) so frequently, I attach some pics here and I did a water change with sand clean up 2 weeks ago.
Any advice on what should I do to maintain clean of my tank ?

 

[Copingwithpods]

Could be diatoms

Quick question, are those aragonite rocks or the like? They look like quarry rocks with granite veins.

 

[Jay365]

Could be diatoms

Quick question, are those aragonite rocks or the like? They look like quarry rocks with granite veins.

I bought rock from petco, not exactly sure the type.
I guess diatoms damage the environment of tank, do they ? Can I do something to clean them up? Thanks a lot

 

[Copingwithpods]

All diatoms do is consume the silicates in New tanks, they will die off once those are down.

As for the rocks, rocks containing iron, granite, quartz and the like can leech these into the water. Depending on the rocks they could also leech silicates (specially granite and quartz) and could make your diatom problem worse.

If they are the rocks I think they are (rocks commonly used for freshwater) another downside is the limited surface area as they are nowhere near as porous as their aragonite counterparts.

I'm no geologist so id wait and get a few more opinions on this and do your own research on the matter.

 

[Intense37754]

No geologist here too but the first thing I thought was dang that water is clear and then saw the rocks. From what I’ve been told freshwater and salt water rocks PH levels differ, I stopped there and stopped inquiring.

And what light are you using? Won’t super white lights attract algae and diatoms?