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FAQs on Freshwater Substrates: Issues, Troubles... Fixing

Related Articles: Freshwater Substrates, Nice bottoms; Choosing the right substrate for your aquarium by Neale Monks, Freshwater Deep Sand Beds Work by Deirdre Kylie, Setting up a Freshwater Aquarium, Tips for Beginners

Related FAQs: Freshwater Substrates 1, FW Substrates 2,
FAQs on: FW Substrate Selection, FW Substrate Physical Properties, FW Substrate Chemical Properties, FW Substrate Amounts & Placement, FW Substrate Changing, Moving, Adding To, FW Substrate Cleaning, FW DSBs,


Discus dilemma! Sys., substrate/pH issue 12/24/10
<Hello Rob!>
First of all many thanks for taking the time to provide this site, it's a fantastic repository of knowledge and it's been absolutely invaluable to my fishkeeping adventures.
Based on this I would very grateful for any advice you don't mind offering on a (long!) dilemma I am facing.
I have a 55 gallon long tank that has been set up for about eight months and which has successfully housed five juvenile 2"-4" discus (tank-bred S. aequifasciatus) and ten rummy nose tetras for about the last five months. There is a reasonable amount of bogwood in the tank interspersed with lots of Cabomba and other assorted plants with one corner kept clear and covered with Pistia stratiotes to provide a darker refuge spot for the discus. The plants are rooted in a 1.5" deep substrate of white 'river sand' and the whole tank is filtered with a very large 2200lph canister filter with large spray-bars set-up to minimise the current in the tank. The water parameters are: 0mg/l ammonia and 0mg/l nitrite (or there abouts), between 10mg/l and 30mg/l nitrate depending on how recently there has been a water change (which I try to do bi-weekly to keep it below 30mg/l)
<I'd do more often... or use other techniques to keep NO3 under 20 ppm max.>
and a KH usually around 6. The pH, until recently, was hovering around 6.8-7.0 and the discus were feeding and displaying themselves nicely.
Unfortunately some of the Cabomba wouldn't stay rooted in one of the corners of the tank and after replanting it a dozen times I decided to increase the depth of sand in that corner to provide the plant with more space to root in properly. Instead of taking the sensible option and driving the long distance to the specialty discus retailer I normally use I opted to buy a generic brand 'white aquarium sand' from my very LFS, a product the clerk assured me would be fine in a discus tank.
<Mmm, some types of such substrate are okay, others...>
About 24-36 hours after I replanted the Cabomba I noticed that my normally resplendent discus were huddling in their refuge spot, leaning and turning brown. I immediately did a water test and found to my horror that, while the other parameters were normal (slight rise in KH), the pH was now about 8.2!
I immediately started doing small water changes using RO water mixed with a small amount of dechlorinated tap water to help give the water some buffering capacity (the tap water here is very hard with pH 8.0+ and KH 6.0-8.0) in an attempt to lower the pH of the tank again.
<You'll have to remove the substrate>
Even after slowly changing a large volume of the water in the tank over the course of several days the pH kept climbing back to 8.0+, so I went back to the LFS that sold me the sand and the manager confirmed that the white sand I had been sold was in fact 'marine sand' (a fact which you think they might write on the packaging!) and so it seems any attempt to lower the pH of this tank is now entirely pointless until I break the whole set-up down and remove all the substrate.
<This is so>
Surprisingly enough the rummy noses have not been noticeably affected by the change in pH; although they did school a lot more tightly for a while so there was probably some stress.
<Good observation>
Unsurprisingly the discus were extremely stressed for about three or four days and lost most of their colour. Since then however the discus have calmed down and regained much of the colour they lost, and are feeding and displaying well again.
So my dilemma is this: do I break the tank down, start again with new substrate and quickly drop the pH of their water which will be a huge short-term shock to the discus (?),
<I would break the system down, or alternatively vacuum out the new (and some of the old if necessary) substrate... and return all the "sucked out" water... of the currently too-high pH... over time (weeks) of regular water changes, the hardness and pH will drop>
or, now that they have apparently
acclimatised to the new alkaline conditions, is it safer to leave them as they are? Internet opinions about discus and pH seem to be deeply divided on whether discus can live happily in high alkaline conditions, with one half claiming that any pH over 7.5 will kill discus overnight
<Perhaps wild-collected specimens>
and the other half claiming that tank-bred discus will live happily in anything 6.0-9.0 pH so long as the water parameters are stable.
<Captive-produced stock/s are much more resilient to such ranges>
The only other tank-space I have spare is in an unused ten gallon 'Nano' which I don't think would work very well even as a temporary solution.
I am planning on moving the discus in the next year or two into a very large 5x3x2' tank which is currently under construction (and given that the weight of water in this tank will be just under a tonne I'd rather not rush this construction either).
<Best to take your time>
I would also prefer these discus to
be at least 6" or so before they make the move to this new tank as I'm also planning on adding several other large adult discus as tank-mates.
With all these facts in mind what is the best course of action for the well-being of the fish?
<As stated above>
I'd obviously prefer not to break the tank down and further stress the fish if it is unnecessary. Will my discus prosper for a year or so in 8.2 pH water (with heavy filtration) now that they appear to have adjusted to the high pH, or do I need to get them back to a low pH fast?
<Slowly enough... and again, I'd remove the new/calcareous substrate>
Am I right in assuming that there is no way to lower the pH with the sand in place?
<Practically speaking, yes; there is no way... The gravel will dissolve, re-buffering the pH till it is all about dissolved>
I know very little about marine fish-keeping but the sand in question appears not to be aragonite as it is very fine and white and was very cheap to purchase so my guess is that it is a limestone-based brand (?). There was no information on the packet other than "Aquarium sand. For use in Aquaria"!
I apologise if this has been covered elsewhere but from my research I appear to be the first person stupid enough to poison their discus with marine sand.
Many thanks in advance,
<Do write back Rob if this isn't clear, complete. Cheers, Bob Fenner>
Re: Discus dilemma! Substrate issue    12/30/10

Hi Bob,
Many thanks for the advice. I have now removed all the sand and added a discus-friendly substrate (Red Sea 'Flora Base') that will allegedly buffer the pH to between 6.5 and 7.0 and absorb nitrate.
<Ahh, much better, mas mejor>
The pH is now dropping slowly with small water changes. The KH has dropped rapidly from 7 to 3, but seems to holding between 3 and 4 for the time being.
Once again many thanks for helping out.
Rob H
<A pleasure and honour to serve. BobF>

Substrate Help, FW   12/11/08 Howdy Again, Now it's time for FW Tank, version 4. My little Eclipse 12 has been completely torn-down after my last round of fin-rot struck, resulting in my Betta going back to the Hospital he seems to love so much. I have removed the 25 lbs of gravel out, rinsed, dried, and bagged it for future use, replanted the 2 Java Ferns and 1 Anubias in my small 3 gallon tank temporarily, cleaned out the scum, and gone back to the drawing board. <This is a 12 US gallon system: not a lot of space. Stock very carefully, and under stock rather than overstock. Have an article on stocking small tanks in this month's CA; recommend you have a read, especially the bit on 10 gallon systems. http://www.wetwebmedia.com/ca/volume_5/volume_5_3/stocking.htm And no, the extra 2 gallons in yours makes no difference at all.> The new set-up will have a bed of Eco-Complete, 1-1.5 inches deep, 3 rocks, and a centrally located piece of driftwood. The driftwood will be planted with Petite Anubias Nana, The background with the Java Ferns, Corkscrew Val.s, and Aponogeton fenestralis. The large rock will have 3 stems of Deep Red Ludwigia, the foreground will have a few stands of Baby Tears, some Banana Plants scattered about, and maybe, if I can find it, a few stems of Purple Bamboo. It will have my Betta Splendens, at least 6 dwarf Corys, and then....well, here is where I am stuck. <No your really not stuck. What you're describing is ample. I'd actually suggest getting three or four more Corydoras hastatus, so that they feel happy and swim about in midwater. The only other things I'd add are shrimps and snails. Corydoras hastatus is most fun when it's the subject of an aquarium rather than the token bottom feeder. When it's happy, it is super-active and swims about at all levels, more like a tetra than a catfish.> I keep reading about gas buildup in substrates and am trying to figure out the solution. <Doesn't happen in tanks with plants or as small as yours. Don't worry about it.> I read about clams, then read the drawbacks and ruled them out. Read about Malayan Trumpet Snails, but am concerned about the reproduction rate getting out of control. <Melanoides only a problem if your overfeed your fish. They turn excess food and decaying organic matter into baby snails; in a clean tank, there's too much for them to eat, and they breed at about the rate they die. Forget about clams altogether. They don't survive in aquaria.> Manually turning the substrate is undesirable (I really want to have a minimal maintenance requirement on the tank). Then there is the articles about DSB's. AHH!! Stop the madness! <Honestly not a big deal.> So, do I get the Trumpet Snails, then introduce Assassin Snails to control the population? Is there a small fish that would work to turn the substrate better than the snails? Do I forget about turning the substrate in favor of a deep bed to actually reduce O2 in the bed. <Clea helena are great scavengers and burrowers in their own right, so by all means use them instead. They breed, but slowly, and sharing excess snails with other aquarists is easy because these snails are pretty, uncommonly traded, and expensive.> Also, there is the issue of algae eaters. If I go with snails, will they suffice? I really like watching shrimp, but worry they might get eaten by my Betta. Ghost Shrimp have been recommended, and are relatively inexpensive, but how effective are they in keeping the tank algae and slime free? I also have been considering Red Cherry or Bumble Bee Shrimp. <Nerite snails are by far the best algae eaters for any tank.> The more I read, the more questions I have, to the point I'm so confused now I don't even know what I should be asking. Please help Frank <Cheers, Neale.>

Question about sand and filter impellers -- 06/11/07 Hello everyone, <Hello.> I have a question about sand's effect on hang-on filters. I added some extremely, extremely fine sand to my tank (it's by Zoo-Med, called "Repti-sand"). It's made of quartz and is very, very fine and light, so much that it took about 2 days until the water was clear after I added it to the existing tank. Really, it's more like dust than sand. Anyway, I have four emerald Cory's in there now, and they love scooting around in it and it's very soft so it's easy on their bodies. It also hasn't affected my pH. I've had it like that for about a week and a half, and then last night the filter started making some grinding noises, so I pulled it out, rinsed it out (some sand came out) and tried to get it to work a few times. Then I looked online and read about impellers, and I saw that the impeller was broken (its blades go around and around). Do you think it's the sand that caused it, or my jiggling it around and taking it apart a few times trying to get it to work, perhaps not being gentle enough, that did it? That one was a Penguin Bio-wheel, and I got a new one today, an Aqua Clear with the different style of filtration. This one's making kind of a gritty noise as well, and I'm afraid it will break, too. Is this a common problem? Do you think I should get rid of the sand, or at least get some heavier sand that isn't so easily disturbed and sucked up into the filter? I do want to keep some sort of sand because I want to get Kuhli loaches later on. <Sand can damage the impellers of pumps. It isn't common though. I use silica sand in all my aquaria, and while sand sometimes gets stuck inside the filter canister, it doesn't seem to do any harm. But your own mileage may vary! Silica sand in particular is quite heavy and settles very quickly. The only time it gets into the water column (and thus into the filter) is when a big catfish decides to swish into the sand and dig herself a burrow. Small things, like Corydoras, simply don't push the sand far enough off the substrate to cause problems. Now, if sand gets inside the impeller, it can quite possibly cause some rattling noise. In the long term, anything that clogs filter media forces the impeller to work harder, and puts all its components under more stress. You probably want to make sure the filter inlet is far enough above the substrate that the fish can't swoosh the sand into the filter. Adding a decent pre-filter layer to your filter system (such as filter floss) is also a good idea. My gut feeling is that while silica sand has been used for many years by many aquarists without problems, finer sands like your Repti-sand might be just a bit too fine for safe use.> Thanks for any and all help you can offer! I really appreciate it! Allison Evans <Hope this helps. I'm a BIG fan of sand in aquaria, and agree with you that loaches and catfish really benefit from its use. But it does need to be handled properly. Cheers, Neale>

Sand as a substrate for a FW Sys.  12/23/06 Hey there, <<Hi. Tom with you.>> First I want to say how thankful I am for all the information I have received from you all.   <<More than happy to help.>> Here's my question. I am setting up a 55 gallon fresh water community tank and I wanted to use sand because I have used it before and am still using it in my other 55.  I have been told that it can ruin your filter.  Although I have not had any problem, I don't know if it was true or not.  Could you tell me if it will. I am using two penguin 330 bio wheel filters they are both pumping 150 gallons per hour each. <<The rationale from the 'detractors' of using sand as a substrate material is that it might be drawn into the impeller section of the filter causing it to wear out prematurely or fail outright. Considering the 'draw' that the suction tube would need to suck sand from the bottom of your tank into the filter, I find this highly unlikely under normal conditions. As a simple precautionary measure, you might shut down your filters when cleaning the tank during water changes to prevent drawing in sand being stirred up from the bottom. Other than this, I'd say to enjoy the look. Tom>>

Setting up a 90 gallon freshwater 7/31/05 Dear Bob,         I have recently been given a 90 gallon fish tank which I plan to set up with freshwater fish. My father and I used to have several tanks when I was younger but that was several years ago. This is my first go-around in some time. My question is about gravel.         I bought "Filpro Sands and Gravel", which is not quite sand, yet not quite big stones. A little of a mixture. Before putting it in the tank I rinsed it with warm water in a bucket. There was a ton of brown, dirty debris that came out of the gravel. Should I be worried that this dirt will be present in my tank? <Mmm, not really... if most all rinsed out> Will it harm anything if not all of it was rinsed out? <Likely not... most all should settle out, be filtered, w/o livestock for a week or two>          Thank you for your insight and I look forward to your response.                                                                                                            Dan <Enjoy that new system! Bob Fenner>

Chuck Clowns Around with the loaches I have a 90 gallon show tank with discus, clown loaches and Bushynose Plecos. It is decorated with wood and single piece of holey stone which gives the loaches many hiding places. The substrate is typical natural colored aquarium gravel. I was considering removing the gravel and leaving the tank bare bottomed so I could keep it very clean. Is that going to be a problem for the clown loaches?  < I would not remove all the gravel. I would leave about 1/2 inch to 3/4 of an inch of gravel or fine sand. There are bacteria living on the gravel that help break down the fishes waste. If you removed all the gravel you would probably encounter big ammonia spikes every time you changed your filter and that would affect the entire tank. I would service the filter once every two weeks and then gravel vac the substrate on alternate weeks.-Chuck>  James Nyman

- Crushed coral raising pH? - I'm sorry to bother you, but I am totally lost amidst the bewildering array of contradictory information I'm receiving regarding my freshwater tank. Here's my situation: My pH is high and I'm not sure what to do about it. I have a 37 gallon Oceanic tank that has both fish and plants. My substrate consists of gravel/rock and crushed coral for color. <Ding ding ding!> For plants, I have two Amazon Swords, a pygmy Sword, Anubias, Rotala Indica, and Apon. bolivianus. I have 8 Danios (4 leopard and 4 zebra), 15 Neon Tetras, 5 Golden White Clouds, 2 German Rams, and a Gourami. Today I did a 20% water change that brought the pH down to about 7.8 from a high of 8.3. <Ironically the proper pH for marine aquaria> Since I'm a newbie, I hesitant to do anymore water changes for fear of ruining a newly cycled tank. I would rather not force the pH down by using chemicals. I've got conflicting advice. Some say remove the coral, others say leave it, and still others say everything will be fine. <It's the coral that's doing it. It is slowly dissolving and increasing both your carbonate hardness and pH. You'll have a hard time getting it down with chemicals since it will just jump back up. I guarantee you, if the new water you add for water changes and top-off has a neutral pH, once you remove the coral you will have no more problems. Enjoy! -Kevin> Please help! Tom

Can something poisonous have grown inside the gravel during the 4 years of "no fish"? Hi, <Hello> My aquarist asked that I inquire here about my dying algae eaters that has even him stumped. <Well, I'll certainly try to help!> Problem: My Plecos and Chinese Algae Eaters (herein ae's) die after 5 days, but all other fish including Cory cats are fine. <Hmm'¦> Question: Is there some strange algae or gravel bacteria that could be killing these Plecos and ae's? Symptoms: 1. Both the Plecos and ae's happily suck on  everything for about 4 days. Then they start swimming lethargically and bump into things as if blind. The ae's will dart full speed into the glass bleeding from the impact. On day 5, both species float around the tank half dead with their gills barely moving. Day 6 there dead. 2. I've gone through 13 ae's since last December and 3 Plecos since March. 3. They consistently die the same way. <Strange. Are you following a strict QT with these fish when you bring them home? If not, try QTing them in a different tank to see if the same thing happens. This will at least allow you to narrow it down to something either with the fish themselves or something within your main tank.> Possibilities: 1. Poisonous algae? From 1996 to 2000, I kept the tank with no fish. I kept the filtration running, but never changed out the water. When I added my discus and neon's in late 2000, I put in new water and cleaned the rocks and gravel, but didn't take them out of the aquarium. Discus and neon's have been fine since then, but is there a chance something grew inside the gravel during the 4 years of "no fish"? I have taken about 80% of the gravel out and bleach-cleaned it, but this cleaning didn't seem to affect anything. <This shouldn't be a factor.> 2. Lack of food? I keep my tank clean, but always drop a Spirulina disc in the tank when I put in the new fish. However, neither the ae's nor the Plecos will eat these discs. <If they're hungry enough, they'll eat the disks so this shouldn't be it.> 3. Old food? I use Wardley Spirulina Discs. The can is about 7 years old. <This is possible. Try getting some new food and see if it helps.> Not Possibilities: 1. Shock. The last batch (3 ae's and 1 Pleco) I transitioned to my tank over 6 hours, slowly adding my tank water and monitoring the chemicals. The store water was at about 6.5 ph and had moderate nitrates. <Very good.> SPECS Fish spec: 3 Discus, 40 neon tetras, 2 Cory cats - all about 3 years old and healthy. Tank specs: Type - Tropical freshwater Size - 75 GAL. Age - 11 years Filtration - Magnum 350 + dual bio wheel Landscape - white gravel, plastic plants, driftwood, petrified wood. Temp - 78F Ph - 6.8 constant Chemicals - All consistently appropriate for Discus and Neons. <This all sounds good.> Any help is much appreciated! <Do check the food and try a QT period. If these fail then you may have to tear your tank apart and start from scratch with new gravel. Ronni> -Chris

Smoke in the Fish Tank - 02/22/03 Dear crew, <Hello! Ananda here today...> I recently set up a 110  gallon tank for my Oscar and Pleco.  I also bought a 4 inch red bellied Pacu.  I know they can grow to be three feet in length, but I have the 500 gallon wood tank on the list of things to be done.   <Those guys get to be almost as tall as they are long -- you'll need those 500 gallons!> Anyway,  I used play sand for substrate in my tank and forgot to wash it.  When I filled the tank I laid a small sheet of plexi- glass on the bottom to keep the sand from stirring.  After a couple of days I noticed very fine particles of sand/dust in the water that gave it a smoke effect.  I was wondering if I can use a micron filter pad to pull these out?   <Should work. If it doesn't, try a diatomaceous earth filter.> If not is there anything else I can do?   <I used some very densely-woven filter felt used in a power filter to remove a "miraculous mud" substance from some live sand I acquired. I needed to check and rinse the filter frequently -- about every ten minutes at first.> It's been close to a month now and I can't stand the smoke. Thanks for the help. Holden   <You're welcome. --Ananda>

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