PlanetCatfish.com

Hello there.
I have a 10 gallon tank with 13 pygmy cories in it. I recently changed the substrate to silica sand for them. My tapwater has a pH of 7.4-7.6 (with a total hardness of ~200ppm) but after adding the silica sand the pH has gone up to 8.2-8.4, and stays high even after water cjanges. My second tank (20g) doesn't have this substrate and the pH stays constant at 7.4-7.6. I suspect the substrate in the pygmy tank contains calcium carbonate and has affected the pH. The fish look paler, less happy and sometimes flick against the substrate now. All other parameters are fine, nh3=o, no2=0, no3<10ppm. I was thinking of replacing the substrate with eco-complete or laterite. Are these substrate materials safe to use with cories? Hopefully they;ll keep the pH down and help with plant growing. Any advice would be most welcome.
Thanks.

By far the best substrate in my opinion is fine well washed sand many LFS's now stock it, alternatively Childrens Play sand (B&Q) It is totaly inert and smooth grained.

I am not sure about eco-complete or laterite, I think these are substrates designed for plant growth.

Ian

Thanks Ian.

Hi Ian,
I've had problems in the past using fine sand. I kept the sand to anout 1/2" depth but found that under driftwood and stones (where I couldn't get to it to stir it up) the sand was going black and stagnant.

I would not have the sand quite so deep, may be 10 mm (3/8") max. Some Corys just move the surface, the long and saddle snouted species will get right into it and down to the base glass.

Ian

Reply for Ian.
Well I've moved the pygmys to another tank with no substrate and loads of anubias on wood. They seem fine and are still in the water from their old tank. While I'm sorting out some sand or inert small gravel I'll take the chance to slowly adjust the pH from the 8.4 in their old tank to the 7.4 of my tapwater. Then hopefully when I move them back I'll not have rising pH problems in their own tank. Still unsure about using sand though sfter previous experience of it stagnating. I'd like to have rooted plants aswell but the cats should come first.
Cheers.

You could always plant the plants in a higher pile of gravel/plant-stuff, whilst using a thin layer of sand in the rest of the tank.

I thoroughly recommend the play-sand from Whickes, £3.89 for a 25kg bag... Much more than you need for a small tank, of course... But if you've got some space to store it, you've got your life-time supply of sand in one purchase, at much less than a tank-full's bag at the LFS.

I'm all for using the LFS for things, but buying sand and other materials at 300% markup doesn't seem sane to me (and the LFS probably doesn't make much of a profit on it anyways, the profit goes to paying someone that sits on a business that prints fish on a bag and fills it with sand... ).

--
Mats

Good advice MatsP!

I'll back coryman up with regard to sand. it won't go stagnant if it's less than 10mm. as you say, you will have to move around your decor to stir up the sand a bit. alternatively, you would be wise to put the decor in before the sand, so the decor sits on the glass not the sand.

Obviously you can't grow plants in this, so if you want to, i would recommend that you mix sand 50/50 with florite to a depth of about 50mm and top it off with about 10mm of sand. some florite will make it's way to the top, but this will make it look more natural. plant heavily so the roots oxygenate the substrate.

Hope this helps.

I have play sand in my tank with corydoras habrosus. They seem to like it, although after reading this thread I think mine is too deep! I actually have some MTS that help stir it up. Also, my plants do fine in the sand. Good luck!

Rebecca

Thank you everyone for your help.
Play sand it is then. I like the idea of separate planted areas and will probably build a terrace using bits of bogwood. By the way I did an experiment with the old substrate and some I'd used in the past. I half filled some jars with different substrate and topped them up with tapwater (pH=7.4). After 24 hours I measured the pH. All had gone up to above 8! These substrates were all bought from reputable LFSs. Cheers, Pete.

For those in the UK
Tesco is currently offering 'Play Sand' at £1.97 for a 10Kg Bag. for those who require smaller quantities. But Keep an eye out nearer the end of the Summer last year one store reduced their sand to 45p for quick sale.

Hello again,
I've bought some play sand from Wickes and have put a thin layer (5mm) in the tank with the pygmys. Since moving them I've got the pH down to 7.8 from well above 8 and they're looking much happier. Their colours are much more pronounced and they'e much more active. Before I left for work yesterday they were chasing each other around as a big group and cleaning the glass and anubias leaves. Should i be getting my hopes up? They've been getting daily 20% water changes to lower the pH.
Cheers,
Pete.

-Pidge
Take black peat to move the pH and also the KH down.

Hi Durlanger,
Do you mean putting peat in the filter? I'm using a fluval 2 internal filter so I'm not sure if I can incorporate peat but thanks for the suggestion. I'm just trying to get the water in the tank back down to thew same pH as my tapwater.

That was what I meaned, but in a extern of course