Always diatoms

[Aquaph8]

Since the start of my tank I've been plagued with diatoms. I never had any issues in my previous tank and just thought they were something that would go away soon. Now almost two years later they are still here and driving me crazy. This all started when I decided to use all new sand even though I rinsed it really well. I use 0 TDS water and run silicate buster DI. Any thoughts?

 

[ritter6788]

Same here. I've always had them. I removed most of my sand bed but I still have it on the little sand that is left.

Same with cyano. Doesn't matter how much I feed, skim or run GFO, I always have small patches of it.

 

[Aquaph8]

Same here. I've always had them. I removed most of my sand bed but I still have it on the little sand that is left.

Same with cyano. Doesn't matter how much I feed, skim or run GFO, I always have small patches of it.

Which sand did you use?

 

[ritter6788]

Caribsea fine aragonite.

 

[Aquaph8]

Mine was also Caribsea but it was the special grade. Is there anyway it's brand related? Only reason I wonder is its been two years and my old sand never had this problem and it was some hand me down stuff that I barely even rinsed and sat in the bucket for way too long.

 

[impur]

Caribsea fiji pink, I also always have diatoms somewhere in the tank.

 

[mcarroll]

If you're really confident in your setup, your (lack of) over-stocking and lack of over-feeding, you've got to look harder at your source water I think.

Half of that is the RODI water and the other half is your salt mix.

So, I would start by assuming that your TDS meter is either lying to you, or (at best) not telling you the meaningful part of the truth. Forget about TDS numbers for now.

An easy way to test your source water, if possible, is to stop using yours for a while - change nothing else - and see what happens. This can mean buying grocery store water, LFS water, water from a friend's - whatever. In a pinch it could even mean just not doing any water changes for a while so all you have to import is ATO water.

If you see improvement then you know it's time to give the hairy eyeball to your RODI system. If not, then this can be ruled our as a cause.

Alternatively, I have known one or two brands of salt to be the cause of diatoms, so try switching salts for a bag/box/bucket's worth - change nothing else - and see what happens. I have not experienced this issue with Instant Ocean or Reef Crystals, so that could be one set of options. Stick with whichever salt yields an improvement.

-Matt

P.S. Before any of that, if you haven't already... Make sure you have excellent flow. Make sure there are no hiding deposits of nutrients in the sand - which can happen fast in some circumstances - or rocks. Over-stocking and/or over-feeding will make all of these more likely and more severe. Make sure your alkalinity is solid - 4.0 meq/L would be a desirable target - to make sure pH swings are fully minimized. Keep lighting to a moderate 8 hours or less.

 

[Aquaph8]

Thanks for the tips Matt. I've always used Reef crystals and its an SPS tank with lots of flow 3x Tunze 6105 and an mp40. I did go a little deeper on the sand this time around though, maybe it's just catching more stuff.

 

[Bartmmackey]

Blackout the tank. 3 days, you will be amazed. Then clean sand,rocks and water change. This will cut them off at the root...then just prevention steps like rinsing food and good water to keep phosphates low.

 

[mike007]

The use of silica in diatom formation occurs quite rapidly, therefore aquarium water itself may not show any significant level of silica even though diatoms have or are forming. Yet, testing the aquarium water if severe diatom-like growth exists is useful if for no other reason than to determine whether the growth is a brown diatom or possibly that of brown dinoflagellate algae. Some phosphate removing medias also remove silica. Believe it or ro/di units only remove about 90% of the silica from the water. You should test the ro/di water for this.