Pre-edit disclaimer. I wrote this post as I did further research and it's a monster long post. I am not thinking I will start a thread and run an experiment as mentioned previously for the reason I discovered below. I did intend to share my parameters so my fellow coffee lover could compare her situation to mine and maybe we could have a discussion on what might be different prefaced with what causes the reactions we may see to look different. If anyone wants to post tabulated results of personal experience, I think we can open a thread or add it to my bdbs thread to hopefully help others know what they can expect based on some of the details I delve (deeply) into below.
Crazy chemistry time; the CAS number listed for the iron oxide in the MSDS for bdbs is a reference for 1309-37-1, Iron(III) oxide, Fe2O3. This is the red powder form of iron oxide, commonly known as jewelers rouge for those that have seen it, it usually comes in a small cup with polishing pads. Primarily iron(III) is used as a base metal for the production of iron; to say it is red but it's not actually "rust", yet.
When mixed with water it can combine to form Fe(OH)3, hydrated Iron(III) oxide, or if mixed with salts or alkalis and water it combines to form various compounds of various acidic properties which do seem like they would appear as running rust. These reactions can be sped up as
pH drops from 8 to 6.5. The issue with the term rust is that it's not very well chemically defined, but it's a group of different compounds generally known to be affecting a base metal by building its own protective (viewed as orange iron oxide) layer and eating at the minerals underneath. In this case our already red iron oxide could be easily covered and turned into/converted by a rust that is a simple chemical bond onto itself.
As far as different people getting different results, I looked at the SDS slowly this time and it reminded me allot of the ingredients you might see in API or seachems
root tabs. The iron,
calcium,
magnesium and sodium being slightly soluble but also used by plants are also found in the root tabs by API and seachem, with the popular thrive caps containing similar ingredients minus the sodium. If one were using one of these fertilizers and bdbs, in combination with a tank that has less planting than can consume the sodium, iron, and other chemicals, you may make a perfect rust storm, where a differently planted tank with different lights may not.
In addition to the fertilizer variables, the by-product from breaking down
chloramine could be a significant contributor that I do not encounter (I have untreated water) in adding salts, as could be hard water, or water that contains iron salts from a well in an iron mining region. Many ph supplements include an amount of sodium carbonate or bicarbonate that may also be a contributing factor.
Now about mine, so you can amateur scientist and compare with me. All my
test kits are api with the exception of iron, which is a seachem test.
From the tap: My well is a mountain/spring well, I have extremely soft water with very little impurity. 2-3 degrees
gH and kH, my ph stays around 7.2-7.8 seasonally depending on rain. I rarely get a detectable result in iron or copper,
phosphate is about .25. 0
ammonia,
nitrite, or detectable
nitrate.
In my tanks, I do not fertize or add chemicals (even the heavily planted one),
dechlorinator is not necessary either. All my measurable nitrogen by-product is produced by the fish, broken down by various snails and micro-fauna, bio media. My tanks are lit by 12 hours of wide spectrum low level grow lighting and kicked up for 10 of those hours by high intensity narrow spectrum white (~6000k)
led lighting. I
water change at least 50% dilution whenever I water change due to my own mathematical obsessions (water changing less than 50% can never put you "ahead"of the curve). This means if I can only pull down 25% in a tank due to scape or stock it will be drained 25% and refilled 3 times leaving ~45 of the original tank water. Easier is the tanks I can take down to/past the halfway mark and get +50% dilution on the first try. For the first ~3 months in each of my tanks I have always tumbled the surface of the
sand in my siphon while waiting for a healthy population of micro fauna to be able to break down any
detritus, at which point I start using the hover technique to intentionally allow nutrients to break down and enter the sand bed.
In these tanks I water change based on threshold of excess nutrient *or* depletion of hardness. My most commonly achieved threshold is 40-80ppm nitrate. I have never had excess phosphate, copper or iron accumulate beyond the amount tested in my tap while in a tank so I haven't set a threshold for those. My second most common threshold hit is minimum kH, we water change a tank whenever we get below two drops on the drop test, at or below one drop with this type of test indicates less than 1 degree and could be well mean zero, leading to a pH crash. My heaviest planted 29 (with bdbs) depletes the Kh from 2-3 to less than 2 in about 3 weeks, my other tanks (both with and without bdbs) are less planted and typically get to my nitrate threshold within a 3 weeks as well, and I have not seen them deplete the kH significantly, likely due to the lack of plant matter removed. In my heavy planted tank I remove lilies weekly and the carbonates and calcium likely take the free ride to the trash can with them. In most of my tanks I grow
crypt and sword, with my snail population I rarely trim and most things come from the water and back to the water one way or another. I also have a few
bare bottom grow outs that when stocked and growing get water changed at least twice a week, once a week we test all the tanks for anomalies, with the bigger/planted tanks we plan on water changing at least 3 hours of water on testing day. Usually my kids and I do this on Monday or Tuesday afternoons.
There's my water in a summary, after reading about what it would take to have variations, it could very well be that our bags of sand are different in iron content (5-12% certainly isn't very precise), as well as the difference in our locally available water, and even fertilizer, planting, stocking, and lighting habits. I looked up the chemistry stuff thinking to build a rig but after finding the details involved, and knowing I get consistent results (3 different water systems contain bdbs, 3 separate bags of 2 different grades purchased years apart and put in service ranging from 2 years ago to the most recent being 6 months old) I think I would have to use someone else's water to accomplish the goal, or that many of us would need to set up identical rigs, use identical tests (but with our own source water, fertilizers and other variables we consider our version of normal) and share the results in a tabulated manner.
Do you see any significant difference in my source water and yours? Maybe in our planting/stocking?
*I want to yell out to everyone that I am not saying my way is "the"right way. You can do it however you want and be just as right, I do love the look of the tanks that run all the chemicals and
co2 etc. I'm just looking for notes so we can see why my result using bdbs may be different at a chemical level, and I know my way is not the most common*
Here's a shot of my "heavily planted" 29, considering it's un-fertilized I think heavily planted is an ok description it's the one that's ~6 months old it contains a few
amano shrimp, 4
Otto's, one 5-6 year old
clown pleco, a few juvenile
mystery snails (bred in this tank, then the mother was moved), handful of
ramshorns, 5 (purple morphs)
harlequin rasbora, 3 remaining rummynose (my lfs got a few bad batches back when the tank was new and still owes me a dozen once they find a different supplier) and 6 of my cull grade endler hybrids I just like the patterns on so I kept them. There are 3 separate lillie's, one mother sword and 3 of its propagations, some various smaller plants like crypt wendtii etc and a bunch of
rotala trimmings. We lovingly call this the "trash can tank" as the
corner filter was built from an actual trash can, and the original inhabitants and a bunch of the plants were headed to the trash can when a friend of mine had to move with very little notice.
On the subject of the cost savings of
diy stuff, since I'm sure I have lost most everyone with the science junk, this tank including a dollar per gallon 29, siding glass lid,
heater, pump, substrate and
cave thing cost me less than $100. Since I used more than a bag and a half of bdbs (80ish lbs) after washing to get the depth I wanted, that alone would have cost me $70+ worth of the cheapest black sand at petco, and I cannot find an SDS for that one to figure out what it is anyways.
The "black
aquarium gravel" I bought back 2 years ish ago has been nothing but awful as it's just a paint/ceramic coated quartz and the coating is chipping off a couple years in; so not all praise be to the expensive "aquarium specific" products either...
I am superbbummed for KatLovesCoffee not finding a match using this sand but that does happen. I can definitely see why she tried it in the first place and am glad we are talking about it now. Knowing what I know about the sand, I likely wouldn't use it for khuli loaches unless I could find the super fine version of it. My local tractor supply doesn't carry that grade so it would defeat the purpose (for me) in using a cheap readily available substitute product if I had to special order it. At least it's easy to suck sand and fine gravel out of a tank to switch though, just take the bell off your siphon and the sand comes right out into your bucket, skim the water off, spread the sand on a baking sheet and dry it in the oven for it's next job.
