Tank 1 - aka the
Shrimp tank - Maintenance, water parameters, fertilizer
This installment is going to be about my maintenance regime, water preparation and dosing - and a bunch of other stuff - for this particular tank
- see
above post #17 for for details about this tank. Most of what I write below applies to my other tank as well.
Maintenance
Daily
My lights come on around noon - my ramp-up starts at 11:30am and reached the preset level at noon. If I am home, I usually feed my fish the first time at 2pm (I mostly work from home). When I am not around, I use an
Eheim food dispenser loaded with
Bug Bites - the Eheim won't dose very consistently to put it mildly, but among the ones I’ve tried, this is the best for small granules - forget using the Eheim for flake-food - it’s close to impossible to adjust the dosing for flakes.
Fortunately I get to feed manually most of the time or have my wife doing it. I usually feed tiny quantities of whatever I am feeding that day and watch the fish eat for a couple of minutes and then add a bit more. I usually feed once again in the evening, but only a tiny bit (one feeding cycle). One day a week I don't feed at all. I feed the shrimp 2-3 times per week; cycling between algae wafers, mineral- and protein sticks with interspersed cucumber and lettuce. If the produce are not eaten up the day after as most common, I remove it to avoid polluting the water. It’s impossible for me not to the check temperature every day as the gauges are just in front of my eyes on the lit of the tanks, but it’s always a stable 23-24 C (~74 F). In addition I check the TDS a couple of times a week with my
Hanna DiST 1 TDS meter which usually hovers around 100 ppm. (my TDS meter uses a 0.5 conversion factor, so 100 ppm correspond to 200 uS/cm).
Monthly
Once a month I clean the HOB filters. The mechanical filters (sponges) gets a rinse and squeeze under under hot water in the sink. The Seachem Matrix bags gets a clean in the water I drain from the tank - I know the filter media only accounts for a fraction of the beneficial bacteria that lives in the substrate, but I still try to be gentle with the bio filter media. I also clean the sponges on the Pat Mini’s under hot water - often I end up cleaning those every time I do a water change - the sponges are small and dense and sucks up a lot of detritus - I like these small filters a lot btw. I do a deep cleaning on all my filters - impeller etc. every 3-4 months unless I notice any obvious performance degradation. I use glass covers on my tanks so I clean those as well every 2-3 months or so.
Water Change
Before water change (WC)
Before draining the water, I turn off all filters (and heater) and do the plant trimming; remove any dying or struggling leaves or leaves that have grown too big and weed out the floating plants. If I occasionally notice any unseemly detritus buildup I try to remove it or at least stir it around gently with a fine net hoping the draining will catch it or eventually the internal filters when they come back on. I can’t safely vacuum in this tank regardless of how gentle I would be not to disturb the substrate. Not only because of plants density, but also because of the many shrimplets of various sizes.
My useless tap water
All of my city water runs through a household water softener (the city water is very hard here at 20-22 GH). The only by-pass we have is for the taps outside the house which are shut off 5-6 mo/year due to the arctic Minnesota winters. The softener uses potassium chloride (KCL ) for ion exchange (most households in the US uses cheaper NaCl) that traps the Calcium (Ca) and Magnesium (Mg) and some other minerals. The softener alleviate lime and scale buildup in the pipes and allow you to use less detergent and soap. The downside is that the water taste less than ideal and you have to make sure you get enough Ca/Mg/minerals etc. through your diet as drinking the tap water wont give you any of that… I wonder how many are aware of that(?). I am not 100% sure, but I believe in Europe its mandated to have a by-pass on the kitchen/drinking/food prep tap - smart! Our tap water comes out at “zero” GH as expected and a TDS currently around 275 ppm - not surprisingly the water is very high on Potassium (K) no one in our household suffers from Potassium deficiency
🙂 but it's likely better for us than the high levels of Sodium we would get if using NaCl.
With my current tanks I’ve always used an RODI system (Reverse Osmosis Deionizer system) - I am using the
RO Buddie 100 GPD (380L per day) with the optional Deionizer. Way in the past I would mix the RODI water with the tap water to reach my desired TDS and KH and to get rid of the excessive K (or Sodium for quite a while before switching to KCL) and remineralize from there. I eventually decided to lower my WC amount and do 100% RODI water instead. It allows me to get my water exactly the way I want it with very little left to chance of collateral damage from seasonal variation and compounds that may be in the tap water. For instance, with Copper (Cu) our city water report from 2021 states that 90% of households tested below 0.37 ppm, and none tested "high", high is presumably 80% of the EPA limit or higher. So the only thing I can safely say is that my tap water Cu level is below 1.0 ppm (which is 80% of the EPA limit of 1.3 ppm). Either way, I wouldn't consider my tap water to be suitable for my invertebrates (Snails and Shrimps) - as a matter of fact, it’s potentially lethal. And of course, the water report only gives a snapshot of what is going on at the time of measurement, so relying on say the base Nitrate levels from the tap water and dose on top of that can be problematic. I know for instance that our water plant is mixing a varying degrees of surface water from lakes and ground water throughout the year so parameters are bound to vary quite a bit. I wish I had access to a stable and superb source of tap water or rain-water that I could just use straight up with whatever minerals I would need to add, instead of the time-consuming and wasteful RODI water (more than 90% of the water that runs through the RODI unit goes to waste! - that's a terrible waste of a natural resource ).
Water change amount and frequency
Since this been a fully matured, grown-in tank for a long time now, I started to wonder at some point if it would make sense to tweak the water change amount and possibly frequency - if I could do this without harm it would be less of a waste and work - as noted above. I do WC’s mainly to get rid of waste, algae spores, pathogens and of course to replenish fertilizers and minerals. In the ideal world I would have an automated system that continuously would feed clean, perfectly remineralized water into my tanks. I don’t think there is any such thing as too much water changes as long as we replenish minerals and fertilizers to keep water parameters stable. My world is not ideal however, so instead I am making my periodical WC water in our laundry room using a very wasteful RODI system and haul 20 L (5.5 US Gl.) buckets through the house when I do my water changes
I didn’t seriously start to tweak my WC amount/frequency until quite recently. In the past I usually did a bit over 50% per week. When I started tweaking it, I slowly dialed it down to see the impact of gradually going from over 50% to ~35% weekly (its one less bucket and likely over 200 L of drinking water saved) and when that seemed to be sustainable over several months, I then started to tweak the days in-between WC’s by letting it run to 11-12 days and this is essentially how the tank has been running for the past 4 months or so. It’s not that I have softened up on the importance of regular WC’s. I am still a strong believer in frequent large WC’s on new immature tanks especially and tanks with a high metabolic rate - be it from a high stocking level vs. plant mass or CO2. It’s a tricky topic when asked, and not knowing all the subtle details in-depth, I would always default to at least 50% weekly. Over the spring/early summer I had an almost 5 week run without water changes and very inconsistent dosing due to traveling etc. - it was obviously not ideal for this tank (or the other tank). The TDS spiked to well over 150 ppm and the tank started to show signs of neglect - definitely waste buildup, but nothing a couple of frequent WC’s, filter cleanings and a big trim couldn’t fix. Healthy mature tanks have a certain resilience it seems.
Water preparation
I usually make the RO water a day before the WC to let the water age; to degas any excess CO2 and to make sure it reaches an appropriate temperature. Before I started doing the aging I would just throw in a powerful heater and a powerhead and wait for the water to heat up. Since we keep that part of the house at 22-23 C pretty much all year around (heated in the winter - A/C in the summer) and the laundry room is often a bit warmer than the rest of the house due to the heat dissipation from washer/dryer etc. , my WC water and tank water differs no more than 1-2 C (so with ~35% WC the temperature drop in the tank is no more than a quarter degree Celsius or so). Usually an hour or so before I add the water to the tank I transfer it from the plastic drum to the buckets and do the remineralization and the fertilizer in the 20 L buckets and stir it up a bit to make sure everything is dissolved.
Fertilizer and Remineralization approach
Micro/Trace dosing
For traces in this tank I currently use
NilocG Plantex / CSM+B (see the trace spec below). I make it in batches of 750 ml. with RODI water added ~30g of Plantex, 0.3g Ascorbic Acid, 0.3g of Potassium Sorbate. I shake it well until everything is dissolved and there is no residue at the bottom (takes quite a while) and store it in a dark place. The bottle lasts for several months (4-5 months or so). Now, one problem with these dry trace mixes is that I really can’t be 100% sure I get the right blend when I make the batch. When I look at the glass jar I transferred it to, it’s pretty obvious that the various elements don’t quite mix in proper quantities (likely because of weight and granule size) - of course, the more grams I mix in my bottle the higher the probability I get everything in the specified quantities. I didn’t think of this before
@Happi pointed that out and recommended to use separate elements that can be mixed more accurately in a batching bottle - and it would also allow me to tweak the ratios between the trace elements - a thing we all surely are doing by now, no?
😉 ... I will soon begin mixing my own traces - wanted to do that for a while - just didn't have time to dive in.
I target ~0.7 ppm of Fe for the whole (150L) tank for the duration in between WC’s - split in two equal sized doses. I usually add the Micros a day after my WC or at least several hours later in order to avoid any interaction with the NPK dosing and then again after 5-6 days. I am not super consistent with my micro dosing… sometimes - more often than I care to admit - it just ends up being the dose I add after the WC. I actually got a really cool
Kamoer X1Pro2 automatic doser that I had running for a bit, but my wife started
nagging about the clutter around the tank with the pump, bottle and stuff… especially when she realized its a gadget that saves me like 5 seconds of attention twice a week 🤓… so anyway, I decided to take it down instead of asking for a divorce
(just kidding, I love my wife... and she actually encouraged me to get back into the hobby... bought me
George's book for Christmas... I mean... what's not to love? 🥰 ). I also try to remember to turn off the UV filter if it happens to be on when I dose, in order to avoid breaking down the chelates - that’s also something I often forget.
Macros dosing - Mineral and NPK
I only dose minerals and macro fertilizers (NPK) once with each water change. I always did the so-called
front loading (or at least, I can't remember when I didn’t…) of everything that I guesstimate the tank will need in-between WC’s and so far its been working well. I started with ridiculous amounts of NPK back in the day, but have slowly dialed it down to quantities that are far more reasonable. I think the front loading approach have a couple of additional upsides - besides the obvious, that you only have to remember to dose ones when you do WC. You can optionally select compounds that gives you a blend of everything to reach your targets. For instance I use use Mg(NO3) to get some Mg and all the NO3/N I need and K2CO3 for K and “CO3”.
I measure out the salts on a microgram weight. Sometimes its a bit more and sometimes a bit less, but I try to keep the weight within +/- 10% of my targets. The TDS won't quite add up to the sum of the ppm’s in each compound - as the ionic charge or conductivity (what the TDS meter actually measures) vary among the elements, but I can at least use my TDS meter to make sure I get the dosing reasonably right (except perhaps for the KH2PO4 which is there in a tiny amount). The TDS in my WC water is usually in the lower 90'ties ppm. Before I acquired a TDS meter (was a gift from my wife), I made some monumental and stupid mistakes with my dosing and water preparation. When I started measuring I had an epic TDS in the 1500 ppm range (yes, 1500… it was before I had shrimps in the tank btw.)… as it turned out it was in part because I got the measurements completely wrong on some of the compounds but more so because I used Acid buffers and Alkaline buffers to reach some “magical” pH and KH values that I thought at the time was important…bunk! - we live and learn... hey, but I read it on the internet!
How I approximate my dosing
Something that is often glossed over when discussing dosing is uptake and how to ensure we don't run dry on fertilizer or completely unnecessarily "
overdose"… I know there are plenty of good sources out there on dosing that works - they are mostly empirical results that appears to work, as far as I can tell, and thats fine. I am not pretending to
rush in with anything new here. A work habit of mine is that I like to build an intuition for a topic on my own terms in addition to what I can pick up in journals, papers and my own research - a very common approach I guess. With my dosing I use a simple
model that allows me bounce numbers around to get a better sense of my dosing strategy - without it just being
“I dose x ppm of y because it works - move along, nothing to see here”. I obviously do not know what the uptake is in my tank (that would require a water analysis on a regular basis with sophisticated lab equipment) and while I don’t see much drift in terms of TDS or GH (Ca/Mg stays very stable) when keeping up maintenance, the only way I can really tell if my plants are starving or struggling is to watch and observe and correct if I see any deficiency symptoms, such as if new or younger leaves are not doing well or signs of algae. However, nothing really tells me if my dosing is
over the top… Unfortunately, there are not a whole lot of data points (that I am aware of) that gives a clue on uptake so I have to guess, but this can be aided with some easy math. If I can make a
qualified guess on the uptake (trial and error, experience, ask more experienced hobbyist) and without trying to account for variation in plant mass it’s fairly easy to roughly estimate the equilibrium for the individual NPK (or Ca/Mg or whatever), and give me a ballpark idea how much to dose so I don't get into trouble and also not induce too much fluctuation . The equilibrium basically means that we find the same amount of a given compound immediately before each water change - I sort of think of the equilibrium value as a
buffer. Lets take a look:
D: The dosing amount in the WC water
U: Guessed ppm uptake (negative ppm)
P: Percentage of water changed (with D amount added to the WC water)
E: Point of equilibrium ppm.
E = U / P - U + D
For instance, if we dose 7 ppm of Potassium and the uptake between WC’s is -2 ppm and you change 40% (40/100) water. The eventual point of equilibrium after a number of water changes will then be E = (-2 / 0.4) - -2 + 7 = 4 ppm.
We never want E to reach zero of course (and negative E is nonsensical) — that’s where deficiency definitely will kick in (likely before) as our tank will run out of the fertilizer compound before the next WC.
For the not-so-math-inclined reader, its easy to show that the above equation yield the value of the equilibrium (E):
Let E be the starting point of the ppm or, as in this example, 7 ppm of Potassium.
E = D * P + (E + U) * (1.0 - P)
WC 1: 5.80 = 7.0 * 0.4 + (7.00 + -2.0) * (1.0 - 0.40)
WC 2: 5.08 = 7.0 * 0.4 + (5.80 + -2.0) * (1.0 - 0.40)
WC 3: 4.65 = 7.0 * 0.4 + (5.08 + -2.0) * (1.0 - 0.40)
….
….
WC 13: 4.00 = 7.0 * 0.4 + (4.01 + -2.0) * (1.0 - 0.40) <== Equlibrium!
WC 14: 4.00 = 7.0 * 0.4 + (4.00 + -2.0) * (1.0 - 0.40)
So after 13 periodical water changes E will no longer change and the equilibrium is reached. A value of 4 ppm K, provided the uptake is in the ballpark, is not a terrible amount as a buffer for growth, slipping WC’s etc.
Let’s say we run a full EI tank and do 70% weekly WC and are dosing 30 ppm of NO3 and the uptake is 20 ppm or 4.5 ppm of N - which is quite a lot even for a densely planted high-tech tank.
E = (-20 / 0.7 - -20 + 30) = ~21 ppm.
To me, that looks like a lot of NO3 just sitting there as a buffer week after week…
Anyway, I will dive a little deeper into this in a future journal post
🙂
My dosing numbers (NPK/Ca/Mg)
As mentioned, I have been experimenting with various dry salts to simplify my dosing and reduce TDS for a while and this is the recipe I am currently using for this tank:
CaSO4:
27 ppm of Ca
22 ppm of S
MgSO4:
6 ppm of Mg
8 ppm of S
Mg(NO3)2:
2 ppm of Mg
10 ppm of NO3
2.3 ppm of N
KH2PO4:
4 ppm of PO4
1.3 ppm of P
1.6 ppm of K
K2CO3:
10 ppm of K
0.75 KH
(numbers rounded as appropriate)
Thats it... 5 different compounds that can be bought cheaply and will last me an eternity. I have all the compounds in glass jars and it literally takes me a couple of minutes to weight out and do the mixing.
So my NPK targets for my WC water is:
2.3 ppm of N
1.3 ppm of P
11.6 ppm of K
GH is ~5.5 or (27 Ca / 7.14) + (6+2) Mg / 4.34 = (3.64 +1.84) = 5.62.
KH is 0.75 as noted above. I really just aim for a low, but non-zero KH that also provide me with a decent amount of Potassium from the K2CO3 - lots of natural tropical soft-water ways hardly have any carbonates (CO3) but always
some it seems…. And I add it to have at least some buffering capacity as well. I am not a bio-chemist, and the CO3 interaction, in terms of what it means for our tank environment is still a bit fuzzy to me.
pH. With my low KH thus low resistance to pH change - it’s easy for me to acidify my water using botanicals. Low pH carries a number of advantages including easier uptake for the plants, lower/slower precipitation of chelates etc. and again, resembles the natural habitats of my livestock. Every time I measure it sits quite comfortably between 6.4-6.8 I usually say my pH is ~6.5 - It’s probably been months since I measured my pH to be honest so I don’t exactly know what it is currently.
Ca:Mg ratio ~3.4:1 I am not sure how much the Ca/Mg ratio really matters. I need enough of both for the sake of the shrimps to support their molt and exoskeleton. 27 ppm of Ca and 8 ppm of Mg seems to be good numbers for the shrimps (never seen a bad molt among my adult shrimps) and the rest of my livestock and plants. The numbers are definitely not cut in stone… some shrimp species have a different tolerance level and even some RCS keepers run their tanks at quite a bit lower Ca/Mg levels than me, but make up for it with a diet heavier in minerals.
I came from much higher NPK numbers in the past and have been dialing this down slowly over a long duration of time. This recipe worked well when I did weekly 50% WC’s and the tank seems to do just as well doing 35% each 12 days. To me the important part of not using more fertilizer than necessary is for the sake of my livestock; keeping the TDS low will reduce osmotic pressure/stress and more resemble the livestocks natural habitats - call me a hopeless dreamer, but I think that an overall low TDS is an important factor for the well-being of my livestock - perhaps more important than say specific finely tuned GH or pH levels. Of course it matters a great deal as well what makes up the TDS. I still have a hard time believing that 30 ppm of S from my CaSO4/MgSO4 (or 50 ppm from Cl if I’d use CaCl2) is doing my livestock any good.
I wish I didn’t have to take on 30 ppm of Sulfate from the CaSO4 and MgSO4, but there seem to be no other way around this at the moment (its much worse with CaCl2 which is often advised, where I would have to take on 50 ppm of Cl instead of 22 ppm of S to reach the same 27 ppm of Ca). Dolomite (CaMgCO3) is on my list to try and may be an option worth considering at the expense of some KH increase - I will have to find time to experiment with it - and will put it in this journal if I get around to it. I have tried with Ca Gluconate and Mg Gluconate. Gluconate is an organic compound made from aerobic fermentation of sugar. Especially the high dose of Ca Gluconate needed to reach 27 ppm of Ca appears to cause a very undesired clouding of the water - possibly due to bacterial bloom or some unknown (to me) chemical reaction. I have tried to find a ratio between CaSO4 and Ca Gluconate where it didn’t cause problems, but the ratio ended up being so high (6 CaSO4 : 1 Ca Gluconate) that it wasn’t worth the extra effort. I have noticed some fertilizer products use Gluconate such as Seachem Iron, but with the tiny amounts needed to reach 0.5-1.0 ppm of Iron, the Gluconate will probably not cause any issues at all and Fe Gluconate is supposedly superior to chelated Fe - yet, I have actually seen some postings on other forums from people complaining about cloudy water after using Seachem Iron - anecdotal, for sure.
Is it lean?
If I go by the weekly targeting that we usually refer to and only dose this with my WC water every 12 day and roughly equate that to weekly amounts of NPK and traces it would be:
Conversion factor to weekly equivalent: k = 7 / 12 = 0.583
Macros / NPK
N 2.3 x k = 1.35 ppm
P 1.3 x k = 0.76 ppm
K 12 x k = 7 ppm
Micros / traces
Fe 0.7 x k = 0.4 ppm
Mn 0.2 x k = 0.11 ppm
Zn 0.04 x k = 0.023 ppm
B 0.08 x k = 0.047 ppm
Cu 0.01 x k = 0.00583 ppm
Mo 0.006 x k = 0.0035 ppm
With the exception of Potassium (K), Calcium (Ca) and Magnesium (Mg), I tend to think of this dosing scheme as pretty
lean.
Could I go lower with my “weekly” dosing? Very likely and perhaps I will tweak it a bit... But I need a certain amount of GH (Ca & Mg) to make this work for the Shrimps as mentioned - and since the CaSO4 and MgSO4 i am using for now makes up for about 70% of the TDS in my WC water (when measured), there is not much of a point in trying to squeeze these NPK numbers even further without making other changes, and I obviously don't want to hit some limit where the tank starts tethering on the edge of deficiency symptoms.
If I keep this tank around 100 ppm (it roughly correspond to an EC of 200 uS/cm - my Hanna meter uses a conversion factor of 0.5) that’s still higher than what is measured in many natural water ways. In the extreme end 7-8 uS/cm is routinely measured in Rio Negro - thats probably a non-starter for most plants anyway with no nutrients except for the soil which is also extremely poor. However, many river tributaries in the Amazon river basin where many of our ornamental soft water fish are found measures anywhere from 15 uS/cm (blackwater) to 150 uS/cm (in Juruá for instance) which roughly correspond to a range of 7-75 ppm. So being around 100 ppm is still quite a bit higher, but not terribly so I guess.
That's it! - I don't think I left out anything important about what I am doing. If anyone think otherwise or need me to elaborate let me know
🙂
Cheers,
Michael
😍
with almond leaves though, just saying...). I attribute the well being of my livestock in no small part to the regular use of botanicals. Yes, the tannins turns my water into a color that resembles very thin tea, but I got over it eventually - sometimes I do throw a clean bag of Seachem Purigen into one of the HOB’s for a week or so if I feel the tea is getting a bit too strong.
