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Discussion Starter · #1 ·
Hey all. I have a 54 gal bowfront natural tank. I've noticed in the morning when the light first goes on that my water is cloudy. It clears up as the day goes on. Curious to know if anyone else has noticed this or know what's going on? Thanks!
Ammonia/nitrite 0
Nitrate 5
pH 7.6 range
GH 9
KH 5

Water Plant Organism Terrestrial plant Aquatic plant
Plant Water Organism Sunlight Aquatic plant
 

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Discussion Starter · #6 ·
Hey @mistergreen, I do have a gravel cap. The tank has been running over 2 years and I have a pretty good layer of mulm and silt from built up plant and food matter that I occasionally vac up a bit
 

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I wonder if this could be due to your light and plants. plant growth can temporarily change the chemistry and PH of the water. If you are using a fertilizer the interaction of the fertilizer with PH could cause iron and other nutrients in the fertilizer to precipitate out of the water.

I would recommend you check your aquarium PH just before the lights come on. Then check the PH just before the light turn off. Then do this several days in a row. I have seen in my tank the PH start at 7 in the morning and then increase during the day. When I first noticed this the PH hit 9 just before lights off (no change in behavior of the fish and shrimp). I eventually minimized it by dimming my new light. Now the PH swings is about +/-.2 with a average PH of 7.

Some fertilizers use iron EDTA. However this iron ingredient is PH sensitive. It will disassociate at a PH of 6.5 or higher and the iron will oxide which can possibly make the water cloudy until the iron oxide settles. If you are using fertilizer what brand are you using and how often do you dose it?
 

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Huge pH swings (7-9 during a 24 hour period) indicate that your water is deficient in bicarbonates (as measured with a low KH of <2). Since many plants (about 50% of submerged plant species) can use bicarbonates as their carbon source, a low KH is not ideal for a natural tank (i.e., no CO2 injection). Bicarbonates both prevent diel pH swings and provide much-needed carbon for many aquatic plants. I would add baking soda (1 teaspoon/gal) to get KH up to 4-6 degrees.

You have supported my recommendation for adding chelated iron fertilizers at night or just before lights go out. That's when light and a potentially higher pH would be less likely to degrade the chelator. I think that Fe uptake is rapid enough that an initial night-time uptake would be significant. My book has a scientific figure (Fig II-3 on page 19) showing uptake by Elodea leaves of zinc and copper that is substantial within 2 hours. [The uptake of all heavy metals (zinc, copper, iron, cadmium) by aquatic plants appears to be rapid and unregulated.]

Thus, I tentatively recommend adding one small dose of chelated iron at night. You can use the results (greening up of new growth/and increased growth of floating plants) as rough guides on how much chelated Fe to add. Note: it shouldn't take much (100-200 mg chelated Fe/10 gal tank). To a 10 gal tank, I add a powdered quantity of FeEDTA that approximates half the size of a green pea. Does not have to be exact, but remember that iron is required in small amounts. It can be toxic to plants and stimulate algae at excessive doses.
 

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Huge pH swings (7-9 during a 24 hour period) indicate that your water is deficient in bicarbonates (as measured with a low KH of <2). Since many plants (about 50% of submerged plant species) can use bicarbonates as their carbon source, a low KH is not ideal for a natural tank (i.e., no CO2 injection). Bicarbonates both prevent diel pH swings and provide much-needed carbon for many aquatic plants. I would add baking soda (1 teaspoon/gal) to get KH up to 4-6 degrees.
I have low KH now but in the past is was higher and I still had PH swings. The reason is simple. most of the KH in water is calcium carbonate or magnesium carbonate. Yes plants can consume the carbonate, but when they do that leaves behind the calcium and magnesium. These covert to hydroxides and push PH up. Also when plants are growing they consume nitrates converting potassium nitrate to potassium hydroxide which also pushes PH up. hydroxides have a much stronger effect on PH than carbonates. Over night the hydroxides latch onto CO2 other compounds in the water and stop pushing the PH allowing it to drop does back down to 7.

based on basic chemistry KH doesn't prevent the PH from going up it only prevents it from going down. Also I now have CO2 and still see the swings. The best way i found to reduce the swings is to slow plant growth by dimming the light. When you have acids in the tank they react with the carbonates forming salts that have no effect on PH. Using a sea shell works much better in controlling PH. If the PH is 7 or higher than 7 nothing happens. the solid KH of sea shell stays solid and won't affect the PH of the water. however if the water turns acidic some of the solid carbonate dissolves neutralizes the acids allowing the water to go back to a PH of 7. This is how it works in nature since soils and rocks have calcium carbonate that will react with acids.

Adding baking soda is also not a good idea. That adds sodium pushing up the KH to 4 to 6 with RO water means the water is almost entirely sodium. If you have naturally soft tap water you also have the same problem. in nature fish live in water with a little bit of sodium and a little bit of potassium. If you put fish in water with just sodium they will eventually die. If you put fish in water with just potassium again the fish will die. And it is not only fish. Excess potassium or excess sodium kills people every day. Its a common issue with any animals. and evidence of it occationally shows up in forums:Snail troubles - SOLVED


besides in nature you rarely find sodium bicarbonate or potassium bicarbonate in river or lake water. Most of the time the you find sodium and potassium sulfate, halide, borate or molybdate salts instead. But you frequently find Calcium and magensium carbonates. If you want to be as natural as possible don't add sodium and potassium carbonates to aquariums. its not natural and it is not safe for fish.

You have supported my recommendation for adding chelated iron fertilizers at night or just before lights go out. That's when light and a potentially higher pH would be less likely to degrade the chelator.
If you look at all iron products out their you will find all are chelates but not all chelates are equal. The chelated irons are Gluconate, EDTA, DTPA, and EDDHA. Iron gluconate is rapidly attached by bacteria causing the iron to rust and can cloud water. It lasts about a day but it is cheap. iron EDTA oxides when the PH is above 6.5. It can also cloud the water. I recommended Iron DTPA it is stable up to 7.5 and sometimes up to a PH of 8. Above that it cn oxide and cloud the water but most tanks are below 8. Iron EDDHA looks very promising. Stable up to a PH of 10! However there is a catch. It colors the water red. So of all of the Chelates available the most commonly used ones (Gluconate and EDTA) can cloud the water because they are not optimal for most tanks. UV light does degrade chelates but regular indoor or artificial lights don't have UV so aquarium lights won't degrade the Chelates.

it shouldn't take much (100-200 mg chelated Fe/10 gal tank). To a 10 gal tank, I add a powdered quantity of FeEDTA that approximates half the size of a green pea. Does not have to be exact, but remember that iron is required in small amounts. It can be toxic to plants and stimulate algae at excessive doses.

100 to 200 mg in a 10 gallon is 2.5ppm to 5ppm. based on some information I have seen on line the toxic limit for fish is around 4ppm but PH and oxygen levels affects this. I use only dose to 0.1ppm once a week in my tank and don't have any iron issues. my dose is based on the amount of iron ion plant tissue. Your dose is also the recommendation for iron gluconate. Neither gluconate or EDTA lasts long in most aquariums so you need to dose a lot more and can push it right up to the toxic limit to get plant growth. I use DTPA which is comparable with my PH so I need very little.

Also when the chelate breaks down the iron will oxidize or react with something else in the tank. And that often is Phosphate. Forming Iron phosphate which is not soluble. So if you use the wrong iron you can end up with a phosphate deficiency. Even though you are dosing more than needed.
 

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You have brought up many points. I'll address a few issues here that immediately caught my eye.

First, FeEDTA has a molecular weight of 367 , and iron (Fe) has an atomic weight of 56. Therefore, when you add 100 mg of FeEDTA, you are only adding 15 mg of actual Fe [(56 divided by 367) X 100 = 15% and 15% X 100 mg FeEDTA = 15 mg Fe]. A dose of 15 mg Fe per 10 gal or 38 liters = 0.4 mg/liter (15 divided by 38 = 0.4 ppm). My recommendation of 100-200 mg FeEDTA gives a final concentration in a 10 gal tank of 0.4 to 0.8 mg/l of Fe. This is way below any toxic Fe level and much of that iron will be immediately lost or consumed.

Second, I recommended adding baking soda (Na bicarbonate) on the assumption that your tank with a KH = 1-2 probably had enough Ca and Mg. (Could be wrong, but you seem pretty aware of need for major nutrients Ca and Mg.) Even though plants cannot use Na, they take it up. So if you are removing and pruning plants, you are also removing sodium. I've calculated that the amount of Na in 1 tsp per 10 gal tank is not enough to inhibit plants. A little sodium is good in many situations. Also, I assume that you will be doing water changes. Therefore, recommending a one time addition of 1 tsp baking soda/10 gal to get your KH up is not unreasonable, especially in this situation where you are injecting CO2.

Third, only light below 520 nm wavelength was shown to degrade FeEDTA (my book, p.168, Fig X-1). While UV light (250-350 nm) would definitely be responsible for most degradation, there is plenty of blue light (450 nm) in LED setups, so I'm thinking that normal tank light would degrade FeEDTA. However, this requires supporting scientific data, so my recommendation to add FeEDTA at night is tentative.

I don't have time to address all your other points. I find many inaccurate and confusing. And since you are using CO2 injection, a lot of what you have written doesn't apply to El Natural tanks. CO2 injection changes everything.

Bottom Line: If you are happy with your tank and strategy, that's what counts.
 
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