Join 3,372 readers in helping fund MetaFilter (Hide)


Re-booting our aquarium
January 2, 2014 12:52 PM   Subscribe

Mr. brilliantine keeps a freshwater fish tank that I've also grown attached to over the years. Sadly we just lost Big Guy, his pleco. He thinks he got him around 1997, so he definitely had a good run but it's still another indicator that the tank is not as healthy as it has been in the past. We've got a few extra stubborn fish hanging on but we've also lost several over the past year. Please help us figure out how to fix this so we can have a flourishing tank again!

I'm not the detail person in this case but I'll try to include as much info as possible.

We had a major black brush algae infestation that is mostly under control now, but we haven't been able to keep most plants alive for at least a year and a half. We have an RO water system and all the buffers and chemicals needed to make it right, but we're afraid to add the wrong chemicals because the current tank water is weird in a way we can't seem to figure out.

pH is mostly in ideal range between 7 and 6.7, though lately it's closer to 6.4 (a little more acidic than we'd like). Nitrates are high, nitrites are good. KH is ok as well, but GH has been off the charts for a while. That's probably our main concern, but we're nervous about directly addressing it since pH, GH, and KH all interact with one another.

We're planning on doing a week of daily 10-15% water changes (RO only) to get the nitrates back down, but we need to know what to start adding to the RO after that to keep it buffered.

The tank is 55gal, with a few algae eaters, a cory, a tiger barb, and a couple of mollies. Gravel and dirt substrate with two teeny, sad-looking plants. We have a light on a timer so that's adjustable if needed.

Any advice on how to get our water back to ideal or suggestions for good boards I can ask would be greatly appreciated!
posted by brilliantine to Pets & Animals (7 answers total) 1 user marked this as a favorite
 
Do you add bacteria to your tank water? I buy something labelled as a 'weekly cleaner' from my aquarium shop - it supposedly contains bacteria which help to break down nitrates. Seems to help lower the nitrates in my tank, anyway.

To remineralise the RO water, you ought to be able to just add some ordinary tapwater that's been left in a bucket for a couple of days to remove the chlorine.

Another issue is the stuff that rots at the bottom of your tank - uneaten food, fish poop, plant debris etc. This releases a lot of nitrates. I find the best way to deal with that is to use one of those siphon things that vacuum all of the dirt out of the bottom of the tank; I siphon out about 25% of the water that way about every 10 days. The downside for you is that you have dirt as part of your substrate, and most of that would end up being siphoned out. A lot of people have a gravel-only substrate for that reason.
posted by pipeski at 1:24 PM on January 2


If your nitrates are high and your fish load is as low as you indicated, I'm thinking that there is some source of decaying organic matter in your tank, perhaps in the filter, or more likely, your substrate. Do you vacuum your gravel when doing water changes?

Growing plants successfully in an aquarium requires balance of lighting, CO2, and macro/micro nutrients, and is honestly a bit of a black art that people can get obsessive about (check out plantedtank.net). What kind of lighting do you have going? An upgrade might be in order. However, there are some plants that will grow fine in any kind of lighting. Your best bet is to acquire these plants. They might be expensive but they are nigh-indestructible: Java Fern, Anubias, Java Moss.

I know that big water changes are controversial. I have had success with fixing troubled tanks by doing 50%+ water changes, often over several consecutive days (50% wc a day for 3 days, say). I was not using RO however, and you have to be very careful about temperature matching your tank water when doing things like this.
posted by sid at 2:20 PM on January 2 [2 favorites]


Also, is there a reason you're using RO water? I did my fishkeeping using strictly tap, and had decent success. RO can cause more issues than tap, and unless you are attempting to keep or breed finicky or fragile species of fish or there is something seriously wrong with your municipal water supply, I would suggest revisiting the decision to use RO water.

Obviously you need to treat your tap water using the appropriate conditioner. I suggest Seachem Prime.
posted by sid at 2:23 PM on January 2 [1 favorite]


Lighting: a GLO fixture with 2 T5 lights. Started using RO water because the local tap was too hard and he read that RO was recommended in order to manage the levels needed for a planted aquarium. We can re test and see if it's better than it was, or try mixing tap into RO.

We vacuum the gravel when we do water changes (and lose some substrate) and have cleaned out the filters (the right way, without losing all the beneficial stuff). We can also look into changing more of the substrate in case something got buried.
posted by brilliantine at 4:44 PM on January 2


We had a major black brush algae infestation that is mostly under control now, but we haven't been able to keep most plants alive for at least a year and a half. We have an RO water system and all the buffers and chemicals needed to make it right, but we're afraid to add the wrong chemicals because the current tank water is weird in a way we can't seem to figure out.

This might be a bit of a shot in the dark, but is your water too still? The black brush algae, high nitrates, and lack of plants are making me wonder if oxygen is circulating through the water properly. You might want to try adding a couple airstones, bubblers or even one of those little Whisper water filters that creates a mini-waterfall -- you should be able to pick all of that up for ten or fifteen bucks and the circulation might help keep your plants happier at least, so it might be worth trying out just to see if it makes a difference.

Also, in terms of the nitrate problem, I would combat that with plants rather than water changes (though I think your idea about water changes is a good one for the general health of the tank, and if it's at all doable, I'd keep up the daily 10-15% changes for the foreseeable, not just the next week. At least in my experience, you're a lot more likely to run into problems erring on the side of too few water changes than too many). The plants should also act as natural water filters, which can't hurt, and in my experience they do a lot to stabilize a tank once they get settled in. If your plants are running into problems, you might also want to get some of those fertilizer tabs to push into the substrate by their roots -- even though your substrate is partially organic, it might not have enough nutrients at this point.

If you're not too happy with your substrate in general right now, you might also want to add some small stones, rocks and driftwood (I'd be nervous about adding new substrate itself while your tank is unstable, because disturbing the substrate that's there might destabilize the tank as a whole even more). You can even get some ornamentation/driftwood/rocks with plants attached, though to be honest I've never done that.

In addition to the plant species mentioned up-thread, I've had a lot of luck with crypts. They tend to "molt" their leaves when you first plant them, so for the first couple weeks you might have to do a bit more vacuuming than usual to make sure you don't get dead leaves adding too many nitrites, but once they're settled in they seem to be extremely hardy. They are slow-growing and do well with low light (especially the green rather than the red crypts).

Be careful when you're doing the vacuuming, though, because in an older tank like yours, you can release bubbles of dangerous bacteria by disturbing the substrate too much/in the wrong spot (dangerous to the fish, not to you).

pH is mostly in ideal range between 7 and 6.7, though lately it's closer to 6.4 (a little more acidic than we'd like).

I've always read that it's more important that your pH be steady than that it be neutral. If you're trying to adjust the pH using chemicals, that actually might be causing enough shifts in the pH to harm your fish and plants -- for what it's worth, I would try to manipulate the pH as little as possible. It might not be optimal, but as long as your pH is above 6.0, I don't think it's an emergency (< 6.0 is when the water starts getting too acidic for some of the "good" bacteria).

KH is ok as well, but GH has been off the charts for a while. That's probably our main concern, but we're nervous about directly addressing it since pH, GH, and KH all interact with one another.

Started using RO water because the local tap was too hard

What is your KH now? A higher KH is going to get your water more basic, which would be good for your pH, and it will make your water a little harder -- I'm wondering if your water is actually too soft/your KH too low right now. If you want to try making the water a bit harder, you can mix a few bits of cuttlebone into the substrate to add some calcium to the water. Another relatively gentle way to raise the pH would be to add a crushed coral filter, but the cuttlebone is so cheap and easy I'd at least try that first.

When you say that GH is off the charts, how so?

Also, do you have a thermometer in the tank? I doubt that such a large tank would have an issue with temperature fluctuations or anything, but you might want to check issues like the water temperature being too low or unstable off the list since you're troubleshooting anyway.

suggestions for good boards I can ask

My personal favorite is the Planted Tank, but Fishlore is good, too.
posted by rue72 at 5:48 PM on January 2


You've had some good suggestions, I'd look at possibly getting a new tube for your light, even though to our eyes the lights can look fine, they can loose some of their effectiveness over time, tubes should be replaced yearly, replace only one at a time as the sudden increase in light can throw the plants into shock, though this is more of a problem in salt water tanks.

As others have suggested, I would also add aeration and some good bacteria, you can buy bacteria packets at most aquarium/pet stores now a days, but the old fashioned way was to get some gravel from a healthy tank to seed yours.

Also, yes you have to cleaning your filter to leave the good bacteria behind and keep the bacteria happy, but make sure the water can still circulate through the filter with no worries and that the solids are removed.

This is probably obvious, but you have cut back on the amount of food as your fish have died off right?
posted by wwax at 7:08 PM on January 2


So, I'm overall skeptical about buying bottled bacteria for your tank, but I haven't been in the hobby for many years and it's possible that there are now viable bottled bacteria products on the market. This web site claims that there are now several brands of bottled bacteria that work well, I would advise you to look into these if you're going the bottled bacteria route.

That being said, there are no species of bacteria that can break down nitrates within the confines of your tank. My understanding is that these types of bacteria are exclusively anaerobic, and you don't want anaerobic zones in your tank. The only way to remove nitrates from your tank are water changes, or many very healthy, rapidly-growing plants.
posted by sid at 1:37 PM on January 3


« Older Current and former McDonald's ...   |  I've been tasked with moving t... Newer »

You are not logged in, either login or create an account to post comments