Tank wont clear up - over taken by diatoms

Hello!
I have a 36 gallon bow front with a Fluval 206 canister filter.
Stocked with a BN pleco, 14 rasboras, 6 panda cory, and a bolivian ram.
All tank parameters are good.

The problem started when I decided I was going to go to real plants for a more natural look. Things were going great for about a month and then the diatoms took over. Every single plant was getting a thick layer of black causing them to die and contribute to the problem. I since then removed all of the plants (except 2, 1 of which is attached to wood and has been in the tank for 5 years no problem) and put my old fake plants back in. I do weekly 30-40% water changes and clean my canister filter out every month or so (this has worked for me for many years) Tank stats are normal and fish inside are healthy the tank just is super unsightly and its bothering me. Now the fake plants are coated once again with diatoms, the sand is no longer a vibrant white its is turning extremely dingy and brown and no amount of vacuuming is taking the color out

This is my plan of action and I was wondering if this will work / is advisable.
-Im going to replace every part of my filter minus the media basket and remove the hoses and soak them in hot water to try and kill off any diatoms that could be living in there.
- the fake plants im just going to toss in the garbage and buy brand new ones (theyre starting to fray and not look so good in the first place)
- remove / replace all of the current sand in the tank
- clean the inside glass / bottom really well to remove as much diatoms as possible

The only part im unsure how to handle is the two real plants I have left. They have minimal diatoms and one is attached to drift wood and my BN pleco loves it. Is there any way to kill off the diatoms on the plants without harming the plants? ive heard soaking them in a hydrogen peroxide and water mixture could help. Would just placing them in chlorinated water do the trick?

I just really don't want to have them come back full force like they are now.
I know diatoms are a normal part of a cycling tank but this tank has been cycled for years and has been a problem for about 3-4 months now. (i also tried phos guard with no luck)
I have only every changed the substrate once before (it was gravel but now is sand) and that was about 3-4 years ago so im not sure if that is contributing to the problem or not.

Any other advice would be greatly appreciated.

 

I would take small steps and go slow with regular water changes... Sounds like your cycle may have crashed... Bummer but not the end of the world.... I've done this adding too many plants at once. However it was lots of willow clones and I'm not sure if submerged plants do the same but I guess they could.

I have no proof but I think the bacteria can starve when lots of plants are added at once, as lots of new plants will pick up raw ammonia and nitrite and nitrate. Then when the plants inevitably melt back a little the bacterial community takes time to recover. Likely low level ammonia caused the diatoms.

I think if you do everything you listed at once you are more likely to cause a longer delay in getting stuff back to balance.

I might start by testing the water everyday to check the cycle and adjust my water change schedule accordingly. Hope that helps a little.

I tend to do that though. Others with cleaner neater tanks and a familiarity with chemical options are sure to chime in too. Best of luck.

 

You might try Phosguard. It’s worked on my small tank (13.5 gallons). It does come back though when you take it out. It’s best to use small amounts and change once a week.

In my 75 gallons, what worked was carbon, but as soon as I took it out, it started again. Now I’m trying to grow green algae on the rocks (it’s a cichlid’s tank full of rocks) to compete with the diatoms.

I can’t say if it’s working right now but it’s not worse, at least.

Lights out, less light has not helped at all for me. Vacuuming and cleaning the fake plants does not help, it always comes back. I do 50% WC weekly, and that doesn’t help either.

For me it's the rocks leaching silica. It will take years before it stops I’m afraid. Let’s hope the algae works...

 

For me it's the rocks leaching silica. It will take years before it stops I’m afraid. Let’s hope the algae works...

Good point the silica in the sand is adding to the issue. zaxbee if you were to do just the substrate change it could help. Go for a replacement that has no silica.

 

You might try Phosguard. It’s worked on my small tank (13.5 gallons). It does come back though when you take it out. It’s best to use small amounts and change once a week.

In my 75 gallons, what worked was carbon, but as soon as I took it out, it started again. Now I’m trying to grow green algae on the rocks (it’s a cichlid’s tank full of rocks) to compete with the diatoms.

I can’t say if it’s working right now but it’s not worse, at least.

Lights out, less light has not helped at all for me. Vacuuming and cleaning the fake plants does not help, it always comes back. I do 50% WC weekly, and that doesn’t help either.

For me it's the rocks leaching silica. It will take years before it stops I’m afraid. Let’s hope the algae works...

I tried Phosguard a few weeks ago and let it sit in there for two weeks but i didnt notice any benefit. Maybe I will fill another bag and try again. I regularly change my carbon bags monthly maybe ill increase the amount i put in there.

I would take small steps and go slow with regular water changes... Sounds like your cycle may have crashed... Bummer but not the end of the world.... I've done this adding too many plants at once. However it was lots of willow clones and I'm not sure if submerged plants do the same but I guess they could.

I have no proof but I think the bacteria can starve when lots of plants are added at once, as lots of new plants will pick up raw ammonia and nitrite and nitrate. Then when the plants inevitably melt back a little the bacterial community takes time to recover. Likely low level ammonia caused the diatoms.

I think if you do everything you listed at once you are more likely to cause a longer delay in getting stuff back to balance.

I might start by testing the water everyday to check the cycle and adjust my water change schedule accordingly. Hope that helps a little.

I tend to do that though. Others with cleaner neater tanks and a familiarity with chemical options are sure to chime in too. Best of luck.

Yeah I wonder if the plants possibly uncycled my tank. I check water parameters weekly before my water changes and i maintain 0 ammonia and 0 nitrite and usually less than 10ish ppm of nitrate. It is quite a mystery. Ive tried everything and nothing seems to be working. Unfortunately cory cats dont seem to eat diatoms like other fish. Everyone seems healthy in the tank so maybe ill let it run its course another month. I just alwasy prided myself with a nice clean tank with super clear water.
Ill hold off on doing all those things and see if things seem to get better with phosguard back in the filter.

Good point the silica in the sand is adding to the issue. zaxbee if you were to do just the substrate change it could help. Go for a replacement that has no silica.

I do have a slate rock in my tank. Its been in there for years though and never seemed to cause problems. I think part of my problem might be diatoms made it into layers of my sand. When I clean the tank they leach back out into the water column attaching to everything. When i change out my sand ill be sure to find one that says silica free. Its just so strange that it happened all of a sudden.

 

I constantly fight the battle too, for a few months I was scrubbing the walls every single week and it could've been every 4-5 days. It starts out near the sand for me and moves up. I'm gradually adding more plants. Right now 3 walls have the brown algae breaking out and the back wall has green algae. I'm choosing to let the green alone and waiting out the diatomes another couple weeks. I just got some water lettuce today and other plants should arrive tomorrow. I'm feeding them with liquid ferts every 4 or 5 days (I forget too often, time goes too fast!) and root tabs. My lights were on too long, but for 2 months I've been turning them off from 2 pm til 4:30, then off by 9 pm, a total of 8 to 8.5 hours. I've trimmed off leaves as I see them getting black before it spreads throughout the plants, it does slow that down. Doing all I can and appreciate seeing your question and the answers you get. I'm so sorry you're going through this, I understand the frustration.