Roy’s Dolomite Adventure
There has been some discussion recently on this forum about the possible benefits of using CaMg(CO3)2 (aka Dolomite) instead of CaSO4, CaCl2, or MgSO4 as a source of calcium (Ca) and magnesium (Mg) for the plants in our tanks.
I was very ill for 5 months this last winter. Now I have a 30 gallon tank that I have been unable to get into back into ‘balance’ since my recovery with thriving healthy plants. The plants look anemic, for example the leaves of my java fern ‘Trident’ (Microsorum pteropus ‘Trident’) are light green with a darker center vein, roots of all species are not healthy or growing well, necrosis (dead spots) in leaves have appeared on my java fern ‘Windelov’ (Microsorum pteropus ‘Windelov’), my Blyxa japonica is barely growing, and the Marselea minuta is just sitting there not spreading at all and barely forming roots. I also have watersprite (Ceratopteris thalictroides), Cryptocoryne wendtii ‘Bronze’, and Hygrophila lancea in the tank along with the cuttings/plants five species I am converting over from emersed growth to submerged growth.
For the first 3+ months this year I was dosing the same nutrients and dosage levels as I was before I became ill - but the plants did not respond. My dosing for the tank the last 2+ months has included trying additional doses of phosphate (P), potassium (K), nitrate (NO3), CaCl2, and MgSO4, Typically I would do a week or two of increased dosages watching new growth for improvement but saw little of any.
My typical dosages on a weekly basis (without the aforementioned variations) were:
KNO3 = 3/16 tsp / 3X week
K2SO4 = 1/32 tsp / 3X week
KH2PO4 = 1/32 tsp / 3X week
Equilibrium = 1-1/2 tsp / 1X week
CaCl2 = 3/16 tsp / 3X week
MgSO4 = 3/16 tsp / 3X week
Glutaraldehyde (Excel strength) 1 “Initial” & 3 “Daily” doses per week
Liquid Iron = 3ml / 1X week (provides about 0.2ppm iron)
CSM+B = 1/32 tsp / 3X week
My dosages of Ca and Mg above may seem high to some folks but our water where I live Seattle area / Seattle municipal water is very, very soft with typical readings (after sitting 24 hours) of:
PH = 7.0
dKH = < 1.0
dGH = < 2.0
Ca = 7.7 ppm
Mg = 0.9 ppm
no detectable levels of nitrogen, phosphorus, and 0.02ppm potassium
My tank parameters as of last week (6/10/16) were:
PH = 6.4
dKH = 3.0
dGH = 4.0
NO3 = 30ppm
Temperature = 75 degrees
CO2 level = not checked or changed lately; will provide info later – probably about 15ppm
Substrate = calcined clay; Soilmaster Select Grey (discontinued)
Water Changes = Weekly approximately 40%
Lighting: Previously I used a DIY AH Supply 2X39 watt kit with MIRO4 reflector that provided [email protected]
at the substrate level with new lamps and [email protected]
with one year old lamps. Three weeks ago it was time to change the lamps again and I decided to go with the 36” / 46 watt Fluval Fresh & Plant 2.0 which provides me with [email protected]
at the substrate level. I have always run a split photoperiod: 08:00 – 10:00 and 18:30 – 21:00 for a total photoperiod of 5.5 hours.
Here is what the tank looked like a couple of years ago.
And this is what it looks like today including some detail shots of plants with issues.
The experiment (aka adventure):
I am going to use my regular dosing of Macro and Micro nutrients outlined above with the exception of substituting KAL Dolomite (CaMg(CO3)2) ($6.89 including tax for 1 lb) for the Equilibrium, CaSO4, CaCl2, and MgSO4 that I have dosed in the past. Since excess calcium (Ca) can inhibit the uptake of magnesium (Mg) and excess magnesium can induce a deficiency of calcium I will try to use doses of Dolomite that approximate the ppms of Ca and Mg I have used in the past. In addition I will monitor the PH, dKH, and dGH of the tank (after water changes; before dosing dolomite (CaMg(CO3)2) on a weekly basis.