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FAQs on Freshwater Substrates: Changing, Moving, Adding To

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 Substrate Issues, FW DSBs,


Changing substrate, FW     7/26/10
Hello crew,
<Hi Pat. Melinda here tonight.>
I have a 240 gallon freshwater aquarium with 2 canister filters and a sump.
I'm interested in changing out my 3M color quartz substrate from black to white.
My LFS told me that the majority, if not all of my beneficial bacteria is located in the substrate.
Is this true?
<I think your substrate switch should go just fine. As always, keep a close eye on water parameters, but those two canister filters, as well as any biological media you've got in your sump, likely contain plenty of beneficial bacteria to take care of your tank's bioload during the switch.
Your filters are going to do the job for you here.>
Should I forget the idea?
<Heck, no! One thing to think about, though, is the fact that white sand is going to reflect a good deal of light back up at your fish from the bottom of the tank, which can be uncomfortable and even confusing for them.
This can cause their colors to fade. Please do read here on freshwater substrate choices and what you can do to combat the glare caused by white sand: http://www.wetwebmedia.com/fwsubwebindex/nicebottoms.htm
and any linked files above which look interesting to you. As far as your biological filter, you should see no problems during the switch. As an added precaution, you could skip feeding for a few days before and after to
reduce the bioload in the system, but again, you (and your fish) should be just fine.>
Thank you
<You're welcome! Please do write back if you have any more questions.

New substrate
Changing Substrate  5/1/10

Greetings, I currently have a 55 gal tank set up and cycled. I bought it used and it already have gravel in the bottom, I have not had any problems with this tank so far. Currently it houses 8 Pseudotropheus demasoni. The substrate is a similar color as the fish and I would like to change it.
What I was thinking was using fine white sand along with a white crushed coral to help it from getting too compact. The demasoni are happy as can be (without directly talking to them) and I'm afraid that with the stress of getting moved out of their tank, having to do a larger than usual water change and adding the coral is going to disrupt them too much and change the pH. What are your thoughts on this? I know I should be testing the pH already but I'm shying away from testing because I'm too much a perfectionist and would do more harm then good trying to get the water just right. Regards, Paul
<Take a sample of your tank water and a sample of your tap water to your local fish store and have the pH checked. If your pH is already greater than 7.0 then there probably won't be a problem changing the substrate.
Watch for ammonia and nitrites spikes since you essentially will have a "new tank". I would recommend that you don't clean the filters for awhile until the bacteria get established in the new substrate.-Chuck>

Changing Substrate in an Existing Tank   5/3/10
It might be interesting to have a chime in on doing a substrate change without moving the fish. I did this gradually over a few days using play sand.
< Play sand may or may not be a crushed aggregate. If it is crushed then the individual particles with be angular and abrasive to bottom dwelling fish. sometimes this will cause trauma to the mouth parts of bottom feeders and create infections around the mouth and gills.>
This got very cloudy but the fish seemed OK with it.
< I would recommend that all substrates be washed prior to placement in an aquarium.>
May not have the cloud issue with something besides play sand. For me it wasn't dirty sand, the Quikrete stuff that I used is prewashed but still is quite fine and likes to float. I have since added some better sand with a darker color to bring out the spots in my Cory cats.
I found that if you go slow the fish will give you plenty of room without freaking out. I also used two methods to lessen the disturbance. First, and foremost the sand needs to be wet before entering the tank. Large scoops seemed to be fine but the trick is not having the sand float out of the scoop before reaching bottom.
I also used panty hose where I filled it up and sank it to the bottom of the tank and sifted out but grew impatient with that. And to get the gravel out I used a sink strainer so I could lift the substrate without taking any of the water.
Also, adding anything course, make sure not to rain it on the fish.
Now, what I did could have been totally inappropriate but if not perhaps feedback on whether this method is OK if you go slow and gentle on the change.
< Your suggestions on doing the physical act of actually changing the substrate are fine.>
What is the tradeoffs between this and doing transfer and full water change?
<The Ps demasoni are not touchy fish. So it becomes a matter of logistics and time. I would have done it all at once since these fish are fairly
tough. If I was working with a more delicate species, then I probably would have changes the substrate about 1/4 at a time and gauged the reaction from the fish to make sue they are not too stressed.>
Or perhaps a hybrid method of doing a 50% water change which is what I did using the old substrate and water in a holding tank during the change (which I did not).
Come to think of it, I think I'd do the 50% with transplant if I were to do it again. On the other hand, with 19 fish to chase and scoop perhaps not.
That has got to be a lot of stress but I'm not sure which is more stressful.
Finally, if you take water samples to a store GET THE NUMBER and not just "it's fine" as a result. Home testing and this website have been the best combo over trusting anyone with my fishes health.thx
< Good advice, thanks for the comments.-Chuck>

Re: Well Established Tank 7/9/09
Thanks Neale
So, if I have a 40 tank that meets all these parameters but I want to add Kuhli Loaches but want to replace some 1/5 of pea gravel for more sand ... would that set me back as far as when I could introduce the animals?
<Shouldn't be a problem at all; provided the gravel is not part of an undergravel filter, you can replace some or even all of it without harming biological filters elsewhere in the system (e.g., in canister,
hang-on-the-back filters, etc.). Cheers, Neale.>
Re: Well Established Tank 7/9/09

And if I wanted to add a few more taller, flowing plants with the sand exchange? Still okay after a bit?
<Still fine. The point is that 99% of the filtration goes on in the place where water flows; filtration bacteria needs oxygen, and won't live in places where there isn't a current of water bringing them all the oxygen they need. Without an undergravel filter, water only flows across the top of the gravel or sand, so there's almost no biological filtration going on except on the very top few millimetres. This is a trivial amount compared to your canister filter (or whatever). So you're free to change whatever you want in terms of sand, gravel, rocks and plants. I do this all the
time! Cheers, Neale.>
Re: Well Established Tank   7/11/09

At what point would you throw away sand and/or gravel? Would you clean and reuse for years?
<Pretty much, yes. Stir the top of the sand or gravel every month and siphon away any gunk that emerges. If you use an undergravel filter, you'll need to give the whole bed of gravel a good clean every 1-2 years, and that involves stripping down the whole filter. This isn't required otherwise, and gravel or sand can be left in place -- apart from periodic cleaning as mentioned -- for the lifetime of the tank. The only exceptions are situations where the substrate is being used to chemically alter the water; for example crushed coral and coral sand for the purposes of hardening water in Malawi tanks, brackish water tanks, etc. In such aquaria the substrate will probably need to be deep cleaned with hot water, and possibly replaced, every year or two, or sooner, if you notice the pH and
carbonate hardness levels dropping. Cheers, Neale.>

Changing Substrate in a 75 gallon FW 7/15/07 <Hi, Pufferpunk here> I am wanting to change the substrate from my 75 gallon FW from gravel to sand. <Why? Do you have burrowing fish? Sand in a tank that size is a real PITA, as it needs to be thoroughly stirred weekly, to prevent anaerobic pockets (toxic gasses) from forming & killing your fish. In a tank that large, it would become tiresome after a while.> I am wondering what the best method would be to do this, and I am also wondering what the best type of sand to use is? I have that play sand is the best to use because its sterile. Is that true? <Many folks do use play sand for their tanks. Like I said before, I wouldn't bother. Just my opinion. But if you insist--move everything out of the tank & remove all the gravel. Then slowly pour in the well-rinsed sand. It will cloud up for a while. You can try removing the floating particles but adding filter floss to the filter & changing it after it gets clogged. Keep an eye on the parameters. You will be removing a huge chunk if nitrifying bacteria, which may cause a mini-cycle. You can add Bio-Spira to replenish the bacteria. Do not add any other product, than Bio-Spira! Good luck with whatever you decide. ~PP> Thanks in advance for your response.

Changing rocks in an established tank  - 03/10/07 Thank you so very much for your time and help with my occasional questions. My fish and I appreciate it. Hopefully this one is a very quick one. I'm bored with the current color of the gravel rocks in my aquarium, so I bought enough bags of a new color to replace the old ones with. Are there any concerns I should be aware of before making the switch; i.e.. Remove the fish temporarily into a container while doing the change? <<Catching on your fish may prove more stressful than working around them, especially if it is pebbles and not cloudy.  My only concern might be the amount of your bio-filter that will be removed with the substrate.  Might be prudent to remove in smaller amounts over time.>> When opening the bags of gravel rocks, should I wash them first? <<Rinsing will do.>> Should I put a new filter in my tank (old one is okay, but just want to be safe)? <<Not unless you want a new/additional filter.>> Are there any additives or extras needing to be put in the water? <<Aside from dechlorinator, no.>> This is my first ever tank which I set up about one year ago so is well established, no unusual deaths (not counting the live fry eaten by the parents). Been using a product called Nitraban, <<No need to use this in an established tank.>> Do partial water changes regularly to keep from nitrate build up. <<Partial water changes are key to a healthy tank. Keep it up.>> and about once a week drop in an anti-ammonia dissolving tablet just in case. <<This is not beneficial to your tank.  Nitrifying bacteria feed on ammonia, and your tank is well cycled, so no ammonia should be readable; these tabs aren't necessary.>> The youngest fry are currently 2-3 months old -unless I have more hiding somewhere since I keep abundant decor so everyone can hide if they want. Also, my tank is in a room in an underground basement, so it's impossible for any outside light to get in. I don't have a bad problem with algae, but noticed it builds up faster the longer I have the tank light on, often for several hours per day. Tank is by the computer and I really enjoy them, and named most of my fish. I've read that using anti-algae formulas will do something that "starves out oxygen" in the tank. Is this true? <<Can be, are often hard on biofiltration, and ignore the source of the problem. I am not a fan at all.  Try limiting the hours the aquarium light is on.>> I do have an aeration pump.  I've just been cleaning the fake plants and decor by hand and discarding the filthiest of rocks, hence a part of the reason I want to dump the white rocks and put a new color in also. I've already read mollies are a vegetarian type of eater, so am I right to assume it's okay to leave some algae on plants to allow them to peck at? <<Not strictly vegetarians, but certainly need lots of vegetation in their diet.  It is best to leave some algae for them to pick at.>> My Corydoras I read are carnivorous and blood worms are healthy for them. The mollies enjoy them also. Are blood worms healthy for mollies? <<Can be part of their diet certainly.  Do be sure to offer all of your fishes as varied a diet as possible for optimum health. Lisa.>> SK

Switching From Gravel To Sand  - 02/25/06 Hello! Thanks for such a great site! You have already answered tons of my questions. I have one I'd like help with though. I have an established 29 gallon FW tank with gravel. I have a couple critters (an albino Cory cat and a freshwater flounder) which I've read prefer sand. I would like to switch to sand but would like input on the best way to do this. I have a BioWheel but I'm concerned about losing too much beneficial bacteria if I remove all the gravel and then replace it with sand. Also, will this substrate change totally freak out my fish? Should I do this in stages or all at once? Your input is greatly appreciated! Very Respectfully, John Tarr < Move all the rocks and ornaments to the right half of the tank. Use a hose and siphon out the gravel on the left half of the tank. Wash the new sand well and place it on the left half of the tank. Now move the ornaments to the left half of the tank now on to the new sand. Fill the tank up with water. Now repeat on the right half of the tank. This way your fish always have somewhere to hide. Bio-Wheels can handle a pretty good bio-load. If there is a lapse in the cycling then just add Bio-Spira to get things back on track , but I don't think you will need it.- Chuck>

Moving Gravel to a New tank 7/4/05 Hello, Great site. I have a few questions on upsizing my current aquarium. I currently have a 29g and 55g, both community tanks. Fairly light fish load, heavily planted. I am going to move everything into a 125g tank. My questions is about moving the gravel to the new tank. Should I rinse the excess waste from the old gravel? Should I rinse it at all? Should I rinse it in tap water? I want to keep the biomass and the water and the live plants to reduce cycling time. Any suggestions? Thanks, CW < If you have a Marineland filter with a bio-wheel , then you can rinse the gravel with out any loss of beneficial bacteria because it lives on the wheel as well as in the gravel. If you don't then I would gently rinse the gravel in dechlorinated water before placing it in the big tank. I think I would fill a 5 gallon bucket up half way with dechlorinated water and place a few handfuls of gravel from the old tank. The lose stuff should float up in  the water and you can transfer the old gravel to the new tank a few handfuls at a time. Tim Hovanec from Marineland has actually done tests and found the beneficial bacteria was lost when the gravel was agitated too much during cleaning. To cover all the bases it wouldn't hurt to use some bio-Spira from Marineland after the new tank is set up.-Chuck>

Changing the Gravel...Good or BAD? Good morning, I have a recently-cycled 6 gallon Eclipse tank which has held fish for a couple of months.  I have two dwarf gouramis, and a couple of small (<1 inch) albino Cory cats. My question is regarding how to replace the approximately 3-inch gravel substrate I initially put in the tank.  It is the fairly large grain, standard fare that is available at all local fish stores.  After watching my Corys try to extract their food, and other scraps that fall down between the cracks of the gravel, however, it seems that the gravel poses a problem since they can't get to it.  So my question is two-fold: does it make sense to try and replace the gravel with a finer sand that the Corys can operate on more effectively (and how would I best do that)?  and will that affect the bacteria levels in my tank negatively? <Good Afternoon, I would not be too concerned with changing the gravel. I would be afraid that if you did that the beneficial bacteria levels would decline.  The extra food that the Cory cats can't reach should be siphoned out every time a water change is performed. If there is a lot of remnants of their meal remaining I would cut back on the amount of food that's fed to them. IanB> Matt

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