# Tesco cat litter substrate - Pros and cons



## Rasbo (3 Feb 2014)

About a year ago I was lucky enough to get my hands on a second hand Trigon 350 and having read about kitty litter as a substrate I decided to try this as the cost and weight of gravel was going to be substantial. In fact I got all the substrate I needed for under a tenner.

First observation is that it is very dusty and is really difficult to wash being so light. Despite ages washing it the water clouded very quickly, in hindsight I should have drained it again perhaps.

It is a nice colour and really easy to plant into and the water cleared quickly.

Eager to plant I grabbed a few plants from local shops in a rather random way and set about fishless cycling which worked really well. Let down by heater thermostat and filter pump failing so lost a few plants that melted in the elevated temps.

Quickly saw a problem with brown algae which has bugged me ever since. Silicate tests were very high as might be expected and to date I have got through 3 lots of Rowaphos yet still have TDS in or around 450 against tapwater of 350ish. Water changes reduce it a little (RO slightly more) but the sheer quantity is a real bind.

Initial plant growth was good but then tailed off and all old leaves are covered with brown algae and strangely a little BGA. I added some Seachem Nitrogen trying to get plant growth to beat the algae but this has had no noticeable effect.

The tank is not heavily stocked, various barbs (Rosy, Gold, Odessa, Cherry, Checkered and Rhombus) plus a few danios and WCMM. I would not recommend anything as boisterous as barbs with this substrate, any plants without roots are almost immediately uprooted and some with roots are left showing roots with the growth point above the surface.

A dozen otos have not had much impact on the algae either.

The substrate is also very tricky to vacuum, fortunately the fish activity seems to mean that the filters can effectively deal with the waste.

I am now at a point where I must rescape and have taken some vallis and sword plants out of another tank and will replant where the original wisteria was. I have to have plants with roots.

So would I use cat litter again? Not in a big tank with larger fish but I think it ideal for small ones.


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## ceg4048 (3 Feb 2014)

Rasbo said:


> Silicate tests were very high as might be expected


Testing for silicates is your first mistake. Algae do not care about silicates.



Rasbo said:


> I have got through 3 lots of Rowaphos


This is the second mistake. Plants need phosphorous. Even if this stuff actually does as it says, removing PO4 from solution is never a good idea generally.



Rasbo said:


> still have TDS in or around 450 against tapwater of 350ish. Water changes reduce it a little (RO slightly more) but the sheer quantity is a real bind.


Worrying about TDS is the third mistake. Plants do not care about TDS generally, unless the TDS is due to dirty water.

You can always try other types of molar clay that are perhaps a bit heavier such as 1 LITRE BONSAI SOIL - MOLAR CLAY

For plant nutrition, you can obtain low cost fertilizers from any of our sponsors such as
TNC Complete - The Nutrient Company
or Ei Starter Kit - Starter Kits - Dry Chemicals - Fertilisers

Cheers,


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## Rasbo (3 Feb 2014)

So you think I was on the right track with the nitrogen dosing?


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## ceg4048 (3 Feb 2014)

Yes, except you are paying 100X more for Nitrogen than you need to. Click the links I gave and check the prices.

Cheers,


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## dw1305 (4 Feb 2014)

Hi all,
Cat litter is very light, but none of the plant growth/algal problems you experienced are directly cat litter related. 





Rasbo said:


> Silicate tests were very high as might be expected


 Even though the cat litter is silica (diatomite) based <Kulturarvsstyrelsen - Verdensarv: The Diatomite Cliffs (Moler)> diatoms can't use this silica to make new frustules. Diatoms can only extract silicon from the water in the the form of silicic acid (H4SiO4), they can't extract the the silica from the silicon dioxide of the dead cells, it is like quartz, it is pretty much insoluble which is why you get a build up of frustules on the ocean/lake bed. In the case of the Moler clay "_All together, these many diatoms eventually formed a layer that was 60 meters thick; this layer was formed over the course of three million years._" 





Rasbo said:


> and to date I have got through 3 lots of Rowaphos.


 The Rowaphos (Iron III hydroxides) will remove phosphorus and silicates by forming insoluble compounds, trace metal ions like zinc and copper will also be removed by the Rowaphos. I'll ignore silica, but once the PO4--- ions are bound, they are insoluble and unavailable to the plant. Phosphorus (P) is one of the 3 macro-nutrients (NPK) that plants require most of, although they require less P than N or K.





Rasbo said:


> I added some Seachem Nitrogen trying to get plant growth to beat the algae but this has had no noticeable effect


 If you are lacking any of the essential nutrients for plant growth, adding more of another nutrient doesn't have any effect. Although nitrogen, or potassium, are usually the elements that are in short supply, removing any of the macro or micro-nutrients will stop growth. Once phosphorus is limiting it doesn't matter how much of everything else you add, until you add some phosphorus ions nothing is going to happen. 





Rasbo said:


> Initial plant growth was good but then tailed off and all old leaves are covered with brown algae and strangely a little BGA.


 The lack of plant growth probably the nutrients being removed from solution by the Rowaphos. If I ever get visible Cyanobacteria (BGA) it indicates I need to clean the filter media, but others will associate it with low NO3- levels. 





Rasbo said:


> yet still have TDS in or around 450 against tapwater of 350ish..


 This is probably to do with the substrate, Moler clay has cation exchange capacity (CEC) this means that it can exchange ions from binding sites on the clay surface. Because this is exchange ions will go in and out of solution dependent upon the lyotropic series and their abundance in solution <Lyotropicseries>. You can think of it like "buffering", it is a reserve of ions that will go in and out of solution. If you kept on changing the water with 100% RO eventually you would have exchanges most of the other cations for H+ ions and your conductivity would fall.

cheers Darrel


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## I MACDONALD (4 Feb 2014)

I used it too in an attempt to save money but I wouldn't recommend it. Firstly it's slightly soluble, which is why it won't clear when rinsing and also the possible cause of high TDS. It varies from batch to batch but the one I got was raising the PH to between 7.5 and 8 but others have reported the opposite effect and that it made hard water softer. I'm not sure about that one but certainly it worked ok as a planting media for a while although I mixed it with other substrates to give it some body eventually. On it's own it's too mobile and will not stay put so any attempt to bank/batter it up is a waste of time. The slightest movement and it's gone and also fish like Cory love to dig about in it and will move the high bits to the low bits overnight. I even tried building a stone weir to contain it but it still slipped underneath after about a month. Not surprisingly it's virtually sterile so there is very little nutrition so the plants will struggle if not supplemented with ferts. Carpeting plants are also a problem because the activity of the fish and water movement will end up covering them. Algae was no better or worse than any other substrate and as has been explained already there's other possible reasons for that. If you want a cheap alternative and that stays roughly level it might be worth a try but for long term use it's more trouble than it's worth.


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## Rasbo (4 Feb 2014)

Thanks guys, perhaps I should have paid more attention in science classes. I have removed the silca/phosphate remover and will get some dosing salts and see what happens.


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## Aquaticz (8 Feb 2014)

Folks use cat litter and the like because it has a high CEC.  I have done a tank like this and it thrived for well over a year. It does not hold well and tends to flatten out. Initially hard to plant until the substrate settles in. Dusty first few days


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