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Discussion Starter · #1 ·
I could use some help understanding the Water Quality Report for my city (since I use tap water for my aquarium). I know that the water parameters that I start with are important to consider when calculating fertilizer doses.

Nutrient deficiency problems have gradually been getting worse over the past few months in my aquarium. Several months ago, however, my plants were doing amazing. I had had a lot of plant growth and increased my fertilizer dosing over time--but I must need to increase the amounts even more. I don't want to go too crazy with the fertilizers. I'm not the type to just dump something new in and see how it goes--I'm more precise and careful.

A concern of mine is preventing osmotic shock for my fish during water changes. The values in my aquarium are usually GH=8-10, KH=2-3, and pH=7.4. The values of my tap water are usually GH=3, KH=1, pH=around 7.0. When doing water changes I raise the GH of the "new water" from the tap by adding Seachem Equilibrium to match the GH of the aquarium water +-0.5 degrees. Likewise, I use Seachem Alkaline Buffer to do the same for KH. The GH and KH are higher in my aquarium vs. tap due to regular use of Equilibrium (for plants) and seashells in my filter (for more stable KH and pH).

If I am reading my city's water quality report correctly, the annual average is 0.006 ppm of calcium and 0.0019 ppm of magnesium with a 7.3 pH average. Does this mean that my plants are really only getting calcium and magnesium from my water changes when I add Equilibrium? Am I reading this report correctly?

Water Quality (2018 annual?) Report

*Recent news Jan. 22, 2020: water tested in my area has the highest level of PFAS contamination in tap water in the U.S. I don't know if that would have an effect on plants, but it's been a known problem in our water for many years.

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How are your plants looking? That tells you what you’re missing.
Plants do need a bit of calcium. I would buy a bag of gH booster. It’s cheaper than commercial bottles. I wouldn’t mess too much with water chemistry. It’s a hassle. All you need to do is partial water changes and the fish will be fine. No worries of osmotic shock. Fish deal with this in nature when it rains.

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4,233 Posts
I believe you are correct in surmising that your plants are only getting Ca and Mg from the water changes containing Equilibrium. Raleigh water is already way too soft for many plants and your water seems even more deprived of hard water nutrients!

I also don't believe that your fish are in ANY danger of osmotic shock. Osmotic shock is when there are major salinity changes, such as going abruptly from about zero to 2 ppt (parts per thousand), which is 2,000 ppm! (My guppies go from 0 to 4 ppt NaCl during fluke treatment without any signs of distress.) Adding Equilibrium to get your GH up to 8-16 dH doesn't even qualify for concern about osmotic shock.

I looked at the 2018 water quality report. It's hard to believe that the "bean counters"--with their jobs on the line-- would make such an egregious mistake. Mg also has a low level--2.4 ppb (parts per billion).

In Ecology of the Planted Aquarium, Table V-5 (p. 85) shows municipal levels of Ca ranging from 0 to 145 ppm; Mg; 0.0 to 120 ppm. This data was summarized from a 1962 report of 100 largest cities and the 1997 individual reports from several major U.S. cities. So there are city waters that have almost no Ca or Mg.

I would take the 2018 report seriously or at least call the water department for clarification and ask why. (If you do, please let us know!)

Gerald, it could be that even though the water originates from the Cape Fear River system with higher Ca and Mg, the downstream city's Sweeney Treatment plant could lower those levels by processing, dilution, or "whatnot."

Practically speaking... I would definitely add a source of Ca and Mg to your tank.

For NPTers, I don't recommend Equilibrium for tanks with an organic soil substrate. That's because Ca, Mg, K, Fe and Mn in Equilibrium ALL have sulfate as their anion (e.g., CaSO4). Understand that excessive sulfates leach into substrate and are readily converted to toxic H2S. This has been reported by several NPT hobbyists to cause reduced plant growth. That's why my book has its own homemade recipe for adding hard water nutrients to soft water. Most noteworthy, the principal ingredient Ca in my recipe (p. 87) is added as CaCl2, a component of many winter "de-icers." (CaCl2 has the virtues of being immediately water soluble and it will not raise the pH.) The other ingredients (Mg, K) can be added as sulfates.

That said, if you don't have an NPT or an organic soil substrate, Equilibrium will probably work fine.

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Discussion Starter · #5 ·
It's a relief to hear that I don't have to worry about osmotic shock to my fish with normal water changes. I had read somewhere that a change in GH by 0.5 degrees or more could cause substantial stress.

I guess it really is possible that the calcium and magnesium levels are that low. I also noted that the TDS is relatively low (less than 200), along with Iron and a couple of other things. Perhaps part of the treatment process is distilling part of the water? Who knows.

I've tweaked my fertilizing, and added more aeration (room air), and the plants have shown some improvement.
-My anubias sprouted new leaves immediately.
-Water wisteria finally stopped melting, and has slow new growth.
-The crypts have more new leaves and the new leaves look healthier than the old.
-Jungle Vallisneria seems mostly unchanged--the existing thick "robust" and green leaves keep growing like normal and I trim them when they get too long. The other leaves start to brown in the middle or tips, and break off or melt from the tip towards to the base. There is very little new growth; new leaves are pretty skinny and sometimes just die in the manner just described.
-Red temple plant seems generally fragile. Leaves break off easily during water changes, new growth is stunted, sometimes misshapen, old growth tends to turn gray.
-Pothos is invincible. I cut the amount of foliage in half hoping it would consume less nutrients; it may have helped the underwater plants some.
-Various kinds of algae in low-medium amounts that tend to "consume" old weak leaves of any plant.

75 gallon aquarium
Seashells in Canister filter
Sand substrate, Osmocote+ root tabs
Water change at least every 7 days, about 30%
Finnex Planted+ 24/7 light on 15 hours/day (sunrise to sunset type low lighting)
Heater set at 77 Fahrenheit
~30-40g Equilibrium added after each water change (depending on WC amount)
~2.3-3.0g Alkaline Buffer added after each water change (depending on WC amount)
~0.9g Epsom Salt (Magnesium Sulfate) after each water change (depending on WC amount)
6 mL Seachem Flourish 1x/week
3 mL Seachem Trace 2-3x/week
4 mL Seachem Iron 2-3x/week
~0.26g KH2PO4 1x/week (maintain 0.5-1.0 ppm phosphate)
~4.4g KNO3 1x/week if needed (maintain 10-20 ppm nitrate)

Right now my aquarium is stocked very low, so there isn't a lot of carbon from respiration for the plants to use. There is one 3-inch blood parrot cichlid, one 5-inch bristlenose pleco, and one small olive nerite snail. I plan to add more fish soon. I just need to set up a quarantine tank and go through that whole process. There is also a giant natural driftwood log slowly breaking down that surely adds a source of nitrogen/carbon.

Please let me know if you have any suggestions for change that stand out in your minds to help out the plants more.
-Replacing sand with a more plant-friendly substrate, or adding a layer underneath the sand is not feasible for me right now. It is a good idea though. I plan to replace the driftwood log (about 4 ft. long) soon and re-arrange the aquarium. I may replace the substrate or add a layer of something underneath when I do that.
-CO2 injection for plants is a good option. I'm just not up for that challenge plus up-front cost quite yet.
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