Why exactly do we dose EI on alternate days? . . .

[Wookii]

I don't dose EI, but when I add iron at the same time as my weekly all-in-one, the water turns an ugly blackish colour. A couple of times I've dosed ferts, iron, and tannin tea on the same day and had the water turn black. Not "blackwater" tannin stained black, but straight up solid black, so that I could not see the fish or the plants. Attaching a photo as proof- you can barely see the bright blue Betta who is literally next to the glass, and you can see the reflection of my hands, the rest of the water is solid black- you can't see the back of the tank at all. I did not add anything unusual or in a larger dose than recommended.

Again I don't dose EI, but I thought that what you see in my pic is the reason for not dosing iron with the others.

Wow, that is bad! I suspect there must be something else going on there - it was my understanding that the reaction between iron and phosphate produces white precipitate, not black? Does your AIO not contain iron already?

 

[lilirose]

I use EasyLife Profito in that particular tank (it's mid-tech, with easy plants and bio CO2). EasyLife don't list the full ingredients for Profito anywhere. Iron is mentioned in passing as an ingredient on their site, but they also recommend dosing EasyLife Ferro separately. Whether that is down to "please buy more EasyLife products for best results!"or not, I'm not sure - however, I dosed extra iron because I've a süßwassertang rope in the back of the tank which I wanted to grow more quickly, and I find süßwassertang grows faster in the presence of extra iron.

I bought into the whole EasyLife ecosystem last year, it works pretty well in low-tech tanks. But as I use up my stock, I will probably move to something a little more well-targeted for my various tanks, especially as I am setting up several that are high-tech. I've seen EasyLife precipitate out of the water when added to RO in a bucket, too, but I've never seen it precipitate in a tank, thankfully.

 

[X3NiTH]

A couple of times I've dosed ferts, iron, and tannin tea on the same day and had the water turn black. Not "blackwater" tannin stained black, but straight up solid black, so that I could not see the fish or the plants.

Easy Life Profito appears to be loosely chelated as it can precipitate when dosed depending on the pH, it appears metal rich, but maybe not in Iron as the company recommends to dose their other Iron product, but it does appear rich in other metals as Darrel suspected this from this post here.

When you dose a loosely chelated metal mixture into receiving water that will absolutely be out of pH range for the storage conditions in the bottle you are at least guaranteed some precipitation. If you dose this alongside another chelate and one as massive as Tannic Acid I would suspect the reaction would be pretty spectacular depending on the metal being chelated, in this case I suspect it’s the Zinc as it oxidises and turns black if dosed unchelated into neutral pH water. Whether the Zinc has oxidised or not before it’s chelated with the Tannic Acid it certainly does when it’s bound because it’s turned the Tannic Acid molecule opaque to light allowing you to see it, the effect will be temporary though (?hours/days) as the Tannins eventually flocculate and become too heavy to remain in suspension and drop out of the water column.

🙂

 

[lilirose]

Thanks @X3NiTH , I knew "adding these ferts with tannins gives a bad result" but I didn't know the reasons behind it, so I thank you very much for the detail, it's very valuable to me to understand what happened.

When my water turned solid black I first tried adding a HOB stuffed with a bag of activated charcoal for 24h, that did nothing besides upset the Betta. I took the HOB off, then waited four days before I got tired of not being able to see what was happening in the tank, and did another massive water change. Now I just don't add those three things on the same day- it seems to be fine if I dose Ferro on Monday, Profito on Tuesday, and tannins on Wednesday.

 

[Wookii]

Thanks @X3NiTH , I knew "adding these ferts with tannins gives a bad result" but I didn't know the reasons behind it, so I thank you very much for the detail, it's very valuable to me to understand what happened.

When my water turned solid black I first tried adding a HOB stuffed with a bag of activated charcoal for 24h, that did nothing besides upset the Betta. I took the HOB off, then waited four days before I got tired of not being able to see what was happening in the tank, and did another massive water change. Now I just don't add those three things on the same day- it seems to be fine if I dose Ferro on Monday, Profito on Tuesday, and tannins on Wednesday.

Does adding the tannins all in one go not cause a big and sudden pH drop? i would have thought you would be better adding some alder cones for gradual and natural release of tannins?

 

[lilirose]

Does adding the tannins all in one go not cause a big and sudden pH drop? i would have thought you would be better adding some alder cones for gradual and natural release of tannins?

What I was doing in my Betta tanks before this "disaster" was to have the amount of tannins fairly constant by adding some tea made from crushed Indian Almond leaf daily, rather than adding it once a week. Now I add it every third day or so- the Bettas seem to like it and not be bothered by any pH drop (which I have never actually measured TBH).

I don't like to use alder cones in the Betta tanks because they get stuck in the siphon when cleaning, but I use them frequently in my shrimp tanks.

 

[Oldguy]

tannin tea on the same day and had the water turn black.

You probably made ferric tannate which is dark blue/black. It was used to make ink, though I found it to lack opacity when I tried making some and lacked contrast on paper.

I make up my own macros ie pot nitrate and pot dihydrogen phosphate in separate stock bottles. MgSO4 crystals I add as a small fist full at water change. Tap water is moderately soft and contains little or no Mg and I cut with rain water, it therefore has very little in the way of nutrients, hence the Mg.

Iron is via EDTA and comes with a list of trace elements and is kept in a separate stock bottle.

Usually dose alternative days. At water change I double dose with macros and one glug of Fe EDTA & Trace solution. Never had any ppt.

When going on holiday I 'front load' with ferts.

I assume that if its in the water column the plants will take what they need. Its often a matter of balancing light and CO2 more than how/when you dose.

Keep watching your plants. (Not all plants require the same amount of light).

 

[X3NiTH]

You probably made ferric tannate which is dark blue/black. It was used to make ink, though I found it to lack opacity when I tried making some and lacked contrast on paper.

Damn I totally forgot about Iron Gall Ink (Windsor&Newton Black Artist Ink) I’ve used loads of it in the past, Metal Tannates are used for their anti corrosion/fouling properties particularly Iron oxide for blueing steel.

 

[lilirose]

@Oldguy - That is an amazing coincidence of hobbies. I love this forum- after it happened I thought I would never know the details of exactly "why". I have learned so much from this thread!

 

[ceg4048]

I've never been able to find an accurate explanation for this.

I understand the need to store concentrated micro and macro mixes separately to try and avoid the iron and phosphate reaction and resulting precipitation (though of course there are techniques for AIO solutions that we are all aware of), but when dosing EI, there will (or should) always be a prevailing levels of PO4 in the water column, so why does it make any difference if we dose micros and macros on alternate days, vs everyday at half the alternate day dose?

I've read some people say that the iron/phosphate reaction can occur at tank level concentrations, and others say that is nonsense and in tank concentrations are too low for that to happen on any problematic scale. Even then, if the reaction does occur in tank, is that not an argument for ensuring each is topped up daily?

I appreciate it might be wise to wait an hour or so between the doses to allow thorough mixing of the first dose with the aquarium water, so does the alternate day dosing really just stem from convenience for manual dosing?

If so, as we are now in a world where electronic dosers are available to the masses for reasonable cost, would timed daily dosing not create better in tank stability than the alternate day dosing?

The answer to this question is exactly as stated by sparkyweasel in post #5. Yes, it is true that Fe and PO4 reactions "can" occur in some tanks, especially if the water is hard (one will observe the precipitation of Iron Phosphate), however, you "can" get away with dosing both on the same day. There are too many variables to make specific instructions for each case, so EI provides simple guidelines to cover as many situations as possible. This does not mean that the principles should be interpreted as some kind of dogma. Always try to remember that the EI dosing procedure was published years ago at a time when the whole world was paranoid of nutrients, so Barr came up with some simple procedures to help the uninitiated.

Dose any way you wish, daily, alternate days, whatever. The day of rest is simply the result of arithmetic and convenience, since the concentration of nutrients will be sufficient, but, if you want to dose on that day then go for it, but it's unnecessary.

Hope this helps.

Cheers,