Need help with diatoms.

DesertReefT4r · Sep 27, 2019

So the title says it, I have a diatom issue. Its been about 2 months now and I cant get on top of it. Some background on the tank. 75g, 20g sump, RO 150SSS skimmer, filter sock changed every 3-4 days, ~50-60lbs of live rock, 0 tds rodi for top off and water change mixing, no3 2 ppm po4 0.03 ppm, 20k 250W MH lighting. Tank is 16 months old almost 17 months and had no algae issues at all for the first 12 months. Started the tank very slowly, unlit for 3 months, no fish for 2, started adding coral at 5 months and had an awesome start. I had a ATO issue and salinty went down to 1.022 very quickly and after that the tank crashed, coral death and cyano issues quickly followed. After beating the cyano with bacteria dosing and 3 day black out diatoms started to take over. I have tired not doing water changes to prevent any possible silicates from being added, no change. I started doing 5g weekly water changes again, no change. Manual remove, no change. Letting it die off in time, no change. Bacteria dosing, no change. Added more snails, hermits, conch and sand sifting star, no change. Less feeding, no change. Ran some carbon, no change. Did an ICP test and everything was perfect which surprised me a lot. I am going to start the fuge back up, took it off line to increase no3 a while back, to hopefully out compete the diatoms. I have started to consider a reset of the tank and removing all the sand since its mostly the sand the diatoms grow on. It is very strange to have such a large diatom bloom on tank this old and with low no3 and po4 all the time. Does anyone have any other tips to beat this other than black out or a semi reset of the tank??

Iván Olalla · Sep 27, 2019

The only thing you didn't mention was flow...from the pic seems a located issue un the corner, maybe add flow and a diamond goby that moves the substrate

DesertReefT4r · Sep 28, 2019

Iván Olalla said:
The only thing you didn't mention was flow...from the pic seems a located issue un the corner, maybe add flow and a diamond goby that moves the substrate

Flow is from 2 PP-8 powerheads. Pretty good water movement but yes the ends of the tank get the lowest flow as is normally the case with most tanks. Diatomsare going all over the sand bed though even in high flow areas. I tried adding a goby but I have a very agressive psuedochrome that kills new fish so I went with a sand sifting starfish and a conch.

Bret Brinkmann · Sep 29, 2019

What type and how many snails do you have?

DesertReefT4r · Sep 29, 2019

Bret Brinkmann said:
What type and how many snails do you have?

4 large turbo snails, 1 conch, nerits probably about 6, mexican turbos about 6, ceriths 2-3 and 2-3 trochus.

Bret Brinkmann · Sep 30, 2019

I'm surprised the conch doesn't eat all the diatoms as I heard they have big appetites. Or at least fight conchs do. What type of conch is yours? Does it or the ceriths eat any? The snails you have seem like a good amount for your size tank but only a few regularly tank to the sand like the conch and ceriths. I recommend adding more ceriths so even when the diatoms do go away you won't have 2 conchs in the sand as ceriths will wander where ever the food is. My ceriths are very good at cleaning my sand. I never had to clean it. I'm also not sure how many I have in my 29 gallon tank. At least 2 Florida ceriths, about 3-4 Caribbean ceriths, and countless dwarf ceriths. The dwarfs stick to the sand the most.

Diatom growth is largely dependent upon Si. I suspect some of the deaths released Si back into the tank. This would explain why you have diatom growth with otherwise low nutrients.

DesertReefT4r · Oct 1, 2019

Bret Brinkmann said:
I'm surprised the conch doesn't eat all the diatoms as I heard they have big appetites. Or at least fight conchs do. What type of conch is yours? Does it or the ceriths eat any? The snails you have seem like a good amount for your size tank but only a few regularly tank to the sand like the conch and ceriths. I recommend adding more ceriths so even when the diatoms do go away you won't have 2 conchs in the sand as ceriths will wander where ever the food is. My ceriths are very good at cleaning my sand. I never had to clean it. I'm also not sure how many I have in my 29 gallon tank. At least 2 Florida ceriths, about 3-4 Caribbean ceriths, and countless dwarf ceriths. The dwarfs stick to the sand the most.

Diatom growth is largely dependent upon Si. I suspect some of the deaths released Si back into the tank. This would explain why you have diatom growth with otherwise low nutrients.

Its a fighting conch. Si tested at 0.269 when I did an ICP test, that was a couple months ago but issues where the same. I need to do another ICP test.
Yesturday I did a large water change 40-50% and siphoned the sand really well. It was not very dirty or full of fish poop. Got it all nice and white again, today its back to brown. I ordered a microscope to make sure these diatoms are not dinos.

Bret Brinkmann · Oct 1, 2019

Do water changes seem to make it worse?

0.269 ppm Si is actually a decent amount. That may take some time to get used up but it will happen. The snails probably like it though. Diatoms are perhaps their main source for Si.

DesertReefT4r · Oct 2, 2019

Bret Brinkmann said:
Do water changes seem to make it worse?

0.269 ppm Si is actually a decent amount. That may take some time to get used up but it will happen. The snails probably like it though. Diatoms are perhaps their main source for Si.

Water changes seem to not effect it at all, if anything its a little better for a few days after a water change.

Mickey · Oct 2, 2019

Are you sure this is diatoms and not dinoflagellates? The cleanup crew will typically eat the diatoms but not dinos.

There are quite a few rather large threads about dinos that are worth reading.

DesertReefT4r · Oct 4, 2019

MickeysFins said:
Are you sure this is diatoms and not dinoflagellates? The cleanup crew will typically eat the diatoms but not dinos.

There are quite a few rather large threads about dinos that are worth reading.

Waiting on a microscope from Amazon to check for dinos.

DesertReefT4r · Nov 5, 2019

Yep dinos not diatoms. Been fighting for the last month. Tried 3 day black out, doing no water changes, bacteria dosing, feeding more, feeding less, more water changes, manual removal, bacteria dosing. Nothing has helped. I am on day 4 of DinoX. So over this issue.

Mickey · Nov 7, 2019

I highly recommend you read the large threads in this forum about dinos. Looks to me like you've got amphidinium dinos so you might start here https://www.reef2reef.com/threads/amphidinium-dinoflagellate-treatment-methods.365850/ . Another suggestion is this one https://www.reef2reef.com/threads/dinoflagellates-–-are-you-tired-of-battling-altogether.293318/ if the Dino-X treatment doesn't work. Lots of people have had problems with Dino-X so good luck, it does work for some.

Mickey