I have read that Soil Master Select although a cheap and popular alternative to fluorite and eco-complete is known to drastically drop KH levels? Does anyone have any direct experience with the use of SMS as a substrate and drastic drop in KH. I thought that GH was more important with respect to plant growth than KH, but as I understand it a dramatic drop in KH can wreak havoc with PH levels and even lead to PH crashes. I cannot imagine rapidly fluctuating PH levels or a PH crash over a short period of time being healthy for fish or shrimp.

I ask because I want to set up a test tank with SMS and am trying to balance the needs of the fish with the needs of the plants. The last thing I need is for a PH crash or rapidly fluctuating PH levels to wipe out the fish.

Thanks

I use SMS and while there was a minor drop in KH initially it doesn't last long. I rinsed mine thouroughly. Not sure if it matters or not it is just what I chose to do. The substrate is great but I wish i would have gotten the charcoal stuff because the red isn't very pleasing to me.

No problem with fish or shrimp health in this tank. I had a problem with some lava rock a little while back but not with my SMS.

Cool. Thanks for responding CM. That is exactly the clarification I was seeking from an experienced user. I bought the Aquariumplants own substrate which many claim is SMS repackaged. I was unable to get SMS as it is not available where I am. Do you use a light layer of mulm, peatmoss, laterite clay or root tabs underneath or do you use it as is. Thanks.

Hi HS,

How do you like the AP substrate? Says they will free ship it over other products they sell

Hey Mooner. I have the Aquariumplants substrate ready and waiting to set up in another test tank, so haven't used it yet. I have to decide which tank(s) I am going to have to tear down to make room as I have no additional room to set up more tank(s) but have to set up at least 3 more test tanks. I had problems with Aquariumplants when I first dealt with them over shipping delays and receiving plants in pathetic condition. They were very quick to refund my money or exchange plants and since then I have had no problems with them. IME, they have the best selection of healthy anubias plants and I really like their grow your own bulbs, which I have found to have 100% germination rate.

I'm not 100% certain on this but this is what I understand to be the cause of SMS and other high CEC fired clays causing KH to drop.

SMS and other fired clays normally have high CEC's. CEC is Cation Exchange Capacity. Exchange is the important word here because cations (Mg++, Ca++, etc) are exchanged for hydrogen ions, H+. These H+ ions (acid) cause the KH and pH to drop.

If you are concerned with this then you can soak the SMS in a saturated solution of calcium and magnesium salts for a week along with some baking soda to prevent pH going too low. Rinse well and use. When I tried this KH hardly changed at all.

James

O.k. thanks for the info, so when you state saturated solution of calcium and magnesum salts for a week are you suggesting Calcium sulphate as a suitable form of calcium combined with epsom salt for the magnesium salts, or an alternative more suitable form to these. Thanks.

I used calcium chloride rather than calcium sulphate as it's a lot more soluble. Also used magnesium sulphate and potassium sulphate. Can't remember the exact amounts used, it was only guess work anyway. The solution made was around 2000 ppm Ca, 500 ppm Mg and 1000ppm K. I actually used potassium bicarbonate rather than sodium bicarbonate mainly to reduce the amount of sodium ions. Think I made the KH around the 10 mark. The SMS was then added to a bin and the solution was added so it nicely covered it and left for a week.

These are only figures that I guessed at but it seemed to do the trick in preventing KH from dropping when I used it in a tank.

I have also thought about adding ammonium nitrate as ammonium (NH4+) is a cation and theoretically the SMS should be able to hold it in. Even though the SMS holds all these cations in, the plant roots are able to access them.

James

Many thanks for sharing That is quite a clever way to avoid the long term KH issues with SMS. It is certainly something that I will consider employing. The calcium chloride should be easy to get from a pool supply shop.

I use SMS iall all my tanks, all with 0 KH due to my use of only RO/DI water and never experienced any crashes or any other PH issues. My PH is prolly around a 4.7~5.1 and what most would consider scary low but all my Amanos, CRS, RCS as well as fish doing fine.

I think you are scarying youself with a really minor issue that will only last for a few months...if that long Just use it as is and you will be fine.

You might have already seen this, if not, you can see here I do inject lots of Co2 regarldless of my KH of 0. I'm not suggesting that you inject as much Co2 as I do but just trying to show you that I am doing it at a more scarier level than you are/will with no issues.