Diatom Issues - What did I do wrong? - The Planted Tank Forum
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post #1 of 5 (permalink) Old 11-03-2020, 09:18 AM Thread Starter
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Diatom Issues - What did I do wrong?

Hello everyone!

I am struggling with what I suspect is diatom algae. The tank setup has been going on for about 2 years now. The first year and a half I used ADA Amazonia soil substrate, however, I switched over to a different (cheaper brand) after moving apartments. That said, I used the cheaper brand (normal sized) soil substrate for about 3 months and wanted to add a finer powdered layer on top of it. After doing so I noticed diatoms or some sort of brown algae appeared. I didn't wash the substrate before adding it to the tank. I wonder if this is the culprit to my brown algae issues. However, this addition of soil was about 1 month ago.

My water parameters are as follows using the API kit.

PH 6.8
NH3/NH4 0 ppm
N02- 0 ppm
N03- 0 ppm
KH 7
GH 9
Chlorine - 0
I filter the water using a Cotton and Carbon filtration unit. I have been using this water for both my tanks and the other tanks has no issues.

Tank Size Kotobuki 900x30x36 80L approx with substrate and rocks.
Filter Kotubuki SV1200X - Installed on October 17th.
Seachem Phosguard is used in the filter unit.
C02 Injection
Light Twinstar E900 - Recently purchased at the beginning of October. On from 11:00 am to 6:00 pm.
Dosing with Tropica Specialized Nutrition - 2 pumps everyday

Water Changes

I do 1/2 to 3/4 water changes every 4 days to try and remove as much brown algae as much as possible. I have removed the rocks and plants between the rocks and cleaned them from diatoms. Cleaned the glass and all the filter equipment as well.


The filter is a SV1200X by Kotbuki. Discharge volume: 100 V 50/60 Hz approximately 1020 L/h approximately 1200 L/h
There is good flow going around the tank and ample amount of filtration. I don't think filtration is a problem
I continued to use the Ehiem Substrate Pro that was in my older filter and placed that in one of the trays of the SV1200X. I am also using the other media tray with the media that was supplied with the filter.

The overall health of the plants and fish are excellent and growing new shoots and leaves very quickly.

It's just the presence of this brown algae that is covering everything and I would like to know what might have possibly caused it. I am a little unsure with how much Phosguard I should be using nor do I really know how long it lasts before changing out.

Any suggestions on what I should do or should I leave it and let it sort itself out?
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post #2 of 5 (permalink) Old 11-04-2020, 06:06 PM
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You're adding phosphate via Tropica's Specialized Nutrition, then removing it via Seachem's PhosGuard? Why?

Your plants need nitrogen, phosphorus and potassium to grow, but your nitrogen and phosphorus levels are zero. Remove the PhosGuard and add more ferts. Otherwise, algae will continue to grow and out-compete your plants.
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post #3 of 5 (permalink) Old 11-05-2020, 08:55 AM Thread Starter
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So you are telling me that Tropica Specialized Nutrition is the cause for high the phosphate levels.

Make sense, because I used to use the ADA fertilizers which were phosphate free. Sigh...

So how do I reduce the amount of phosphates? Use less Tropica Specialized Nutrition? Shorten the photo period?
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post #4 of 5 (permalink) Old 11-05-2020, 05:49 PM
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You don't need to reduce the amount of phosphate, as it is at zero. Instead, you need to increase the phosphate by removing the PhosGuard and continue using Tropica fertilizer. Plants need phosphate to grow.
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post #5 of 5 (permalink) Old 11-08-2020, 03:26 AM Thread Starter
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Thank you for your help.

What I have done is remove the Phosgaurd and using 2 pumps each day of Tropica Specialized Nutrition.

Before using Tropica liquid fertilizer, I used ADA full range of liquid fertilizers and never ran into such problems.

Maybe I was under dosing with Tropica that coupled with high lighting and C02 injection has created a higher plant demand for nutrients. A total of 2 pumps a day should do the trick. I also use ADA ECA Plus and ADA Green Bacter Plus.
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