Seeking advice regarding a mysterious freshwater aquarium problem

[Kipley]

We have a 50-gal lightly-planted freshwater tank. It’s been up and running for about 9 months. We have 26 fish, ranging in size from adult Yoyo Loaches to young Julii Corys. We have driftwood for our two bristlenose plecos and a couple of phony hollow wood logs for the loaches to chase each other through.

50-gal Aqueon HOB filter and a large sponge filter. Imagitarium aquatic substrate.

We feed a few shredded spirulina and krill flakes, a pinch of sinking pellets, and either a couple of algae wafers, veggie rounds or catfish chips twice a day. Frozen brine shrimp substituted for one meal twice a week.

We do around 30-percent water change every week, syphoning the gravel. Perimeters spot-on.

Here’s our problem: Within a day or two after the weekly water changes a light layer of what looks like dust covers everything. I can rub it off the plants but it just comes back. It covers the top of the sponge filter too. You can see small particles floating in the water before it settles on everything. I should mention that new plants often die soon after we get them so it could be plant detritus.

I don’t know if it’s harmful to our fish but it certainly can’t be good.

Whatever it is, it just keeps cycling after each water change.

Any thoughts on solving our mystery?

 

[FJB]

Pictures of your aquarium (and detail of the stuff you described as growing on surfaces) would go a long way to allow identification and to provide possible reasons and solution to your difficulties. In addition, a better description of the species composition of your fish would help. Specifically, you mention a total of 26 fish, including 2 BN plecos, small cories and yoyo loaches. That is quite a few fish in a 50g, and both yoyo loaches and male BN plecos get large and produce a lot of waste.
30% weekly water change sounds insufficient for that load, and feeding twice daily may be too much. Not really knowing about your plant population does not help in getting a complete picture. The type of lights you have, and the duration of daily ON period, as well as knowing with light is also coming from a window or equivalent also important.
You say parameters are spot on, but that means very different things to different people so it is necessary to describe it better. However, several items in your description, together with perhaps not many plants, point to excess nutrients that may be triggering algae growth.

If the stuff on surfaces is brown/reddish and rubs off with fingers, it sounds like an algal species that is colonizing the surfaces. However, I seem to understand there is also floating 'dust-like' stuff. That also needs to be better described.
Sorry not to be able to better help at this time, but you can provide additional information. Good luck!

 

[Kipley]

Pictures of your aquarium (and detail of the stuff you described as growing on surfaces) would go a long way to allow identification and to provide possible reasons and solution to your difficulties. In addition, a better description of the species composition of your fish would help. Specifically, you mention a total of 26 fish, including 2 BN plecos, small cories and yoyo loaches. That is quite a few fish in a 50g, and both yoyo loaches and male BN plecos get large and produce a lot of waste.
30% weekly water change sounds insufficient for that load, and feeding twice daily may be too much. Not really knowing about your plant population does not help in getting a complete picture. The type of lights you have, and the duration of daily ON period, as well as knowing with light is also coming from a window or equivalent also important.
You say parameters are spot on, but that means very different things to different people so it is necessary to describe it better. However, several items in your description, together with perhaps not many plants, point to excess nutrients that may be triggering algae growth.

If the stuff on surfaces is brown/reddish and rubs off with fingers, it sounds like an algal species that is colonizing the surfaces. However, I seem to understand there is also floating 'dust-like' stuff. That also needs to be better described.
Sorry not to be able to better help at this time, but you can provide additional information. Good luck!

Thanks for your reply FJB. I'm sorry my inquiry lacked the details you mention. Picking up on a response from another forum it would appear we have a brown diatom algae bloom. Since we have an established tank and the numbers are within normal range, there's some other issue causing the algae. I'm thinking a deeper syphoning may help eliminate food for the algae. Also sadly discovered a rotting dead pleco during our wc today. I'm changing from carbon to a floss filter to hopefully pull out the nasties. We used mostly RO water today. Any thoughts re getting rid of the algae? Thanks again for your feedback.

 

[FreshyFresh]

Just curious as to which test kit you are using and why RO water? Water with no mineral content isn't going to help your plants.

To reduce algae, you have to cut your lights on time and cut the amount of food added to the tank.

 

[Kipley]

I'm using the Api Master test kit and their GH test.
One source says the silicate in tap water may be encouraging growth of diatoms. They suggest trying RO water to knock down the algae. I'm more concerned about the algae than minerals for the plants at this point.

Brown algae (Diatoms) - | Aquasabi

Brown layers in the aquarium

www.aquasabi.com

 

[Rbishop]

Get full readings on your tap water after the sample water has sat out over night. I disagree with blindly adding RO without a specific reason such as poor quality tap water.

 

[fishorama]

I think several AC people have the right ideas. Also sometime tap water can be "seasonal" depending where you live. Winter snow or rain & spring thaw, & often where, I live with summer drought. It can affect many parameters.

Don't ignore FF's question on how long your lights are on. That can cause trouble with algae. I almost always go for 6-8 hours of light at most (split time is ok too, say 2hrs in am, 5 in pm).

It does seem like maybe too much feedings for adult fish. Tell us what, beside bottom feeders (my favs!), you have & their sizes, & what plants too. Sometimes the "brown dust" is just fish poo or rotting leaves (or food?) in an old-ish (not brand new) tank set up. Vacuuming is good, so is plant maintenance. Do you remove dying leaves every weekly water change? Some plants are not "happy" in a given tank & will not be worth the effort to try to keep them alive...Sad but true.

Please tell us lots more!! & in a vague way can you say where you live? State (country?), near a big city?, NOT your address. Are you on a well or "city water"?