Pond Boss Forums Thread Like Summary - Does Alum stay dissolved, or does it sink?

If Alum is dissolved in water will it stay suspended? Or even if dissolved in water will it quickly sink to the bottom?

I’m wondering if I have to spread an alum slurry over the whole surface area of the pond because it sinks right away, or if I can slowly add an alum slurry to flowing water, where it will eventually mix into the whole water column.

What do you think?

I'll pass on either or, as I have done both, and I am more comfortable with gypsum application. It also gets me the hardness that I need in my hatchery pond soft water.

I can't remember if it's been addressed, but what about application costs when dealing with alum/hydrated lime? If we're talking about a pond that's big enough to require a boat/barge that can handle a chemical application X 2, what and how would the price affect the overall cost? Kenny, I would think you, Rex, or Scott would have a good feel for it. Of course, mileage $ would have to be left out since it's always a variable.

If one does go the alum/hydrated lime route, then I can't emphasize the care that is needed when applying the lime. Stay dry and have PPE for both eyes and face. I use a 3M Rugged Comfort Quick Latch, and dispose of the canisters after usage. I like this one because it's great protection, sizable, very comfortable, and it allows you to hang it around your neck while you're getting ready.

Story 1) When I was young and handsome(40 years ago), I was carting a pt into the emergency room at Parkland Hospital. Once we were inside, we passed a treatment room, and it had 1 ER dtr, 1 Burn dtr, and 3 nurses cutting the clothes off a man. Turns out he was burnt by hydrated lime while adding it to concrete. He had 1st and 2nd degree burns from the neck down, and was obviously in pain. The potential future debridement would only make the pain worse.

Story 2) I have a neighbor that was in concrete and road construction for close to 45 years. He was prepping soil for a pad that was a continuous pour, and they used hydrated lime to help dry up the soil before the pour. The HL dust got in the cab of the equipment he was on, and got it in his eyes. He bleed from his eyes, had impaired vision for a short time, and was lucky there were crew members close enough to help him flush his eyes. IIRC, he said always kept vinegar and water jugs in his truck in case of hydrated lime burns. His vision got better, but it was a very close call.

So, I don't mean for this to be a "Christmas Story" you'll shoot your eye deal, just be careful. When wet, hydrated lime deserves all of our respect.

All or none. It works by the attraction of negatively charged ions... It flocks and sinks the compound you are after when the correct amount is applied. It falls through the water column slowly, attracting particulates and/or Phos on the way down.
For example. if you mix a slurry of 100lbs per acre ft of water and nothing happens in 48 hrs, you can't go back and "add" to it, you have to start over with a new, higher amount such as 200lbs per ac ft.
You have to make a slurry in a pump tank so the Alum is dissolved before blowing it out over pond surface.

Ted,

I am going to go back down one level from Snipe's excellent advice.

As regards your first question about alum being dissolved or staying suspended:

Imagine putting normal table salt in a glass of water. At first you will see the salt grains settle on the bottom. If you stir it vigorously, the salt will swirl up into the water, and after you quit stirring, a little bit less will be showing on the bottom. Eventually, if you stir it up enough, ALL of the salt will be dissolved and "suspended" throughout the entirety of the water volume in the glass. (We don't actually use the term "suspended" for dissolved materials, that term only applies to discrete particles that remain in a liquid. Also, it is possible to add more salt than your volume of water is capable of dissolving.)

Since you don't want your alum "settling at the bottom of the glass", that is the reason you use a slurry of alum and dump it in the pond slowly and try to spread it rapidly with your propeller wash, etc. If you just dumped in a 100# of alum as golf-ball size chunks, it would sink to the bottom and only very slowly dissolve into your pond water. (And the chunks that sank into the bottom sediment might never dissolve.)

Your next question about things sinking right away refers to the tiny clay particles when they flocculate. (That is just a $2 word that means clump together.)

Have you ever pushed two bar magnets together trying to touch the + end of one to the + end of the other? You can actually feel the magnets repel each other. That is exactly what is happening to the tiny clay particles suspended in your pond water. They have a tiny charge and are repelling each of the other particles.

Once you get the alum dissolved in the pond, a positively charge Aluminum ion will bind to a negatively charged clay particle. It then becomes a neutral particle. These particles are now a little bit sticky. As they swirl around in the water, these particles bump into similar particles and stick together (flocculate). As the clumps grow larger, they sink to the bottom of your pond much more easily.

As for your final question about a half treatment being able to clear half of the suspended clay. Experience shows us that it just doesn't work that way.

Imagine the mice chewed 12" of insulation off of a wire in your truck. It is now touching the frame and causing a dead short. If you wrap tape on 6" of wire, it does not solve the problem, your wire is still going to short.

Even if you knock the negative charge off of half of the clay particles in your pond, they will still stay suspended. They need to clump together with the other particles to drop out of the water column.

I hope that helps understand the "reasons" a little bit more. If not, then Snipe is an actual pond expert. If you just follow his advice, that is usually the best way to get your problem solved!

First, I've used this method many times in quite a few ponds now.
It's not linear as for the amount of Alum used vs what it sinks. Either you have enough for the particles to bind with or you don't.
Think of it like a course spider web, or 1" casting net. As it falls through the water, most particulate just goes through the net whereas a smaller mesh it builds on making the holes smaller gathering more as it goes down. It has to flocculate to work.
Alum is a positive charge by +1 because Alum is +3, sulfur -oxygen is -2, but sulfur and oxygen are non metallic so the positive charge is transferred to those elements.
Clay is a negative charge. and is attracted to the alum. Not enough Alum and the clay particles crash into each other with insufficient force to make contact and "stick".
In most cases, Type S Hydrated lime should be used as a pH buffering agent at half-rate of Alum. Great part is this adds to the positive charge and attracts even more clay in suspension to sink.
The ions only have so much power to attract and depending on the source of suspended clay, you'll be doing it twice if you don't use enough the first time.

Todd tends to go with the safest route when dealing with DIY pond owners. I spread gypsum after every drain and refill on my hatchery pond, it raises the hardness, and clears up the water in a day or two. I had great results spreading gypsum in George Glazener's pond 5-6 years ago. IIRC we added 30 tons, shut off the aeration, and the water cleared up in 3 days.

Highfyler and I treated one of my cow tanks with alum and hydrated lime as a test run, and it cleared up pdq. What surprised me was that even with the cows stomping around in it, the water stayed fairly clear for a few months.

Well, My alum showed up early to the coop. Going to apply it today. Hopefully i'll have a good report for yall on monday.

Bottom line is Alum is not for everyone, whether it be the wrong application or someone who's never done it, it can be dangerous.
I will be the first to admit that after Todd's post, I need to study the Gypsum process but getting it to the site is an issue-for me- in most cases. The difference in cost is not the only factor here but getting 40 bags of Alum vs 10 -12 ton of gypsum into a site was a challenge for me.
I'm paying 40$/50lb bag for my Alum and 8.30$/bag for hydrated lime. I charge $1,000 for app up to 1 ac and 400 per ac above the 1.
Can't speak for Rex or anyone else doing this.
My region is highly regulated on surface water due to being on the Ogallala aquafer and KS law on pond size and location, so I don't do ponds much larger than 5 ac., most are 3/4-2ac.
To this point, I have chosen my battles carefully on a pond I will or will NOT do and to be transparent, I don't treat the acreage Todd or Rex do, but my results with my choice of product have been near 100% success..
I do use both shore app with pressure nozzle and boat application.